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About me: I have a masters’ degree in Infectious Disease Epidemiology from UCLA, a bachelors’ degree from Wheaton College in biology with a certificate in International Community Development, and a masters’ in Greek and Hebrew Exegesis from Gordon-Conwell Theological Seminary. Usually, I am writing and posting bible studies on the Redemptive History Facebook page, but these are not normal times.

I began my career by editing a medical monograph and writing an accompanying peer-reviewed journal article during my graduate studies at UCLA (MPH, Tropical and Infectious Disease Epidemiology). My first publication concerned the excess risk of severe illness or death from a bacterium in raw milk in California. It was featured on the front page of the Los Angeles Times and was debated in the state legislature.

After graduation, I conducted records-based research concerning the efficacy of a poly-pharmacy reduction program for nursing home residents. We focused upon the frequency and severity of adverse drug reactions, and whether our patients could stop taking their medications without needing to resume using them. Textbooks still cite it today.

Paul Terrill MD, FAAFP has been an invaluable collaborator in assessing and compiling many of these resources.

Due to the sudden onset and severity of the pandemic, many journals are pre-empting their normal four-week to six-month process of peer reviewing articles before releasing them for publication. When you look at any research involving Covid-19, it is important to note the status of the article: pre-print or accepted for publication after peer review. Check the comments under pre-print articles. Several major studies were retracted after the peer-review process detected significant issues.

Does Peer Review Still Matter in the Era of COVID-19? — Milton Packer describes the impossible task of vetting medical research

Lancet, NEJM retract studies on hydroxychloroquine for COVID-19

This post addresses issues specifically concerning the delta variant. For information about Covid-19 which does not pertain to delta, click here.

1. How Was the US Managing Covid-19 Until Recently?

Only a few weeks ago, in early July 2021, infectious disease experts were feeling hopeful. As more people received full immunization, Covid-19 cases were diminishing. Reaching herd immunity soon seemed possible. Virtually all Covid-19 cases, hospitalizations, and deaths were occurring in unvaccinated people:

  • For every 147 positive tests, one person was vaccinated
  • For every 259 hospital admissions, one person was vaccinated
  • For every 167 deaths, one person was vaccinated

To see how I calculated the information in this graphic, you can click here: https://denisetplichta.files.wordpress.com/2021/07/jan-1-to-apr-30-covid-stats.pdf

Emerging information about the delta variant is rapidly changing how we respond.

2. Does the delta variant have different symptoms from previous SARS-CoV-2 variants? Are vaccinated people who get infected contagious?

People infected with the delta variant are less likely to experience cough or the loss of smell. The loss of smell usually accompanies a milder infection, so this does fit with the increased virulence we are now seeing. Delta variant infections often produce a headache, runny nose, sore throat, congestion, sneezing, muscle pain, and fever.

To see a full listing of Covid-19 symptoms, click here.

Symptoms which require immediate emergency medical care include difficulty breathing, continuous pressure or pain in the chest, an inability to awaken or to stay awake, a new onset of confusion, or a blue tinge in the face or lips.

Investing in a pulse oximeter to track your blood oxygen level is a great idea. They cost about $20. A normal oxygen saturation level runs between 95–100%. People with Covid-19 can experience a drop in that percentage without realizing it has happened. If it does occur, seek medical attention immediately.

CDC: Symptoms of Coronavirus

MN Dept Health: Oxygen Levels, Pulse Oximeters, and COVID-19 How does COVID-19 affect a person’s oxygen levels?

Fully vaccinated people who get infected often have symptoms of a mild cold. They can still spread the virus just as easily as unvaccinated people.

That is why the CDC now recommends everyone wear a mask in indoor public spaces in localities with high rates of transmission.

Yale Medicine: Five Things to Know about the Delta Variant

CDC: Outbreak of SARS-CoV-2 Infection, Including COVID-19 Breakthrough Infections, Associated with Large Public Gatherings—Barnstable County, Massachusetts, July 2021

CDC: Interim Public Health Recommendations for Fully Vaccinated People

3. How does a virus variant arise?

Random mutations occur due to errors in the viral replication process. While coronaviruses have an enzyme which corrects most of those mistakes, some do still slip through to create a new variant.

Only those mutations which confer an advantage to viral replication, transmission, or survival of immune systems expand in a host population. Since mutations are random, vaccine developers cannot predict in advance what a virus will look like in the future.

JAMA: Genetic Variants of SARS-CoV-2—What Do They Mean?

4. When and where did the delta variant originate?

Originally called B.1.617.2, the delta variant was initially identified in India in December 2020. It appears to have arrived in the US in March 2021, when the nation’s mass vaccination program was well underway. Mayo Clinic maintains a list of the variants of greatest concern world-wide.

CDC: About Variants of the Virus that Causes COVID-19

Mayo: COVID-19 Variants: What’s the Concern?

5. How fast has the delta variant spread in the US?

On April 24, 2021, the delta variant accounted for 0.6% of the SARS-CoV-2 genetically sequenced specimens in the US. By September 18th, that decreased slightly to 98.6%. The CDC’s interactive dashboard shows the proportion of each variant over time for the US as a whole and for each region. It is currently updated every two weeks.

CDC: Variant Proportions

6. What is an R0 number in disease transmission? How has it changed from other SARS-CoV-2 variants? Why are vaccinated people getting breakthrough infections?

An R0 (“R naught”) represents the basic reproduction rate of a pathogen: how many people become infected when exposed to a single case. When an R0 is larger than 1.0, an outbreak is increasing; when it is less than 1.0, an epidemic is waning. Human behavior and the properties of an infectious agent both impact disease transmission, so some variability does exist.

CDC Emerg Inf Dis: Complexity of the Basic Reproduction Number (R0)

Researchers use the R0 to estimate the proportion of a population that must no longer be susceptible to infection to reach herd immunity. That can typically be achieved by a combination of surviving natural infection and immunization.

Diseases with a higher R0 require more people with immunity for transmission to stop.

The original strain of the virus which came from China had an R0 of 2.5; in the UK, the delta variant is almost three times more transmissible with an R0 of approximately 7.

However, on July 29, 2021, the CDC estimated the delta variant is just as transmissible as chickenpox. Chickenpox has an R0 of 9–10, which means that the average person with that virus infects 9 or 10 people. As a result, 89–90% of the population surrounding an infected individual must be immune to prevent spreading that disease.

For those of us too old to have received the vaccine to prevent chickenpox, how many of us escaped infection?

That is why many experts are warning that anyone unvaccinated against Covid-19 in the US will almost certainly contract the infection. Please do not make the mistake of equating transmissibility with severity. Covid-19 is far more dangerous than chickenpox.

Compared to the original strain of SARS-CoV-2, even vaccinated people infected with the delta variant carry 250 times the amount of virus.

A comparison of antibody levels in Moderna and Pfizer recipients revealed over twice the number of antibodies produced by the Moderna vaccine. This is likely due to the increased amount of mRNA in Moderna and the longer interval between doses.

After vaccination or natural infection, when we are exposed to the virus, our circulating antibodies attach to the spike protein of SARS-CoV-2, preventing the virus from entering a cell. When there are more viral particles than available antibodies, the virus breaks through our defenses. How we behave has an enormous impact on the amount of virus we encounter.

Once inside, the delta variant reproduces so rapidly that it can spread before our immune system has time to react, enabling the virus to spread to others. However, the vaccines also produce T cell immunity. Our T cells go on a search and destroy mission, killing any infected cells and neutralizing the virus within them. This significantly shortens how long vaccinated people can spread the virus.

People who are fully vaccinated produce more antibodies and a much stronger T cell response than those infected with SARS-CoV-2 one year ago.

In addition to people carrying a greater amount of the delta variant of the virus, one study found that people with the delta variant shed it for an average of eighteen days vs. thirteen days for other variants. That may also be why the R0 is higher.

Three-fourths of transmission is occurring during the two-day window before symptoms develop, Days 4–6 after exposure to SARS-CoV-2. Compared to people who are unvaccinated, fully vaccinated people are two-thirds less likely to spread the virus to others.

Lancet: Lifting of COVID Restrictions in the UK and the Delta Variant

JHU: Measuring Disease Dynamics in Populations: Characterizing the Likelihood of Control

Lancet: Clinical and Virological Features of SARS-CoV-2 Variants of Concern: A Retrospective Cohort Study Comparing B.1.1.7 (Alpha), B.1.315 (Beta), and B.1.617.2 (Delta)

Lancet Preprint: Transmission of SARS-CoV-2 Delta Variant Among Vaccinated Healthcare Workers, Vietnam

Fox News: If you aren’t vaccinated and haven’t had COVID, you will get delta variant: Brett Giroir, former Trump health official urges Americans to get vaccinated

MedPage: We Can All Benefit from Helping Patients Understand Breakthrough COVID—Here’s How to Approach the Conversation

JAMA: Comparison of SARS-CoV-2 Antibody Response Following Vaccination with BNT162b2 and mRNA-1273

MedRxiv: Virological and Serological Kinetics of SARS-CoV-2 Delta Variant Vaccine-Breakthrough Infections: A Multi-Center Cohort Study

MedRxiv: SARS-COV2 Mutant-Specific T Cells and Neutralizing Antibodies after Vaccination and Up to 1 Year After Infection

MedRxiv: Transmission Dynamics and Epidemiological Characteristics of Delta Variant Infections in China

7. Is the delta variant more dangerous than the others we have seen?

Unfortunately, the delta variant is causing significantly more severe illness and death than the other variants we have seen so far during this pandemic.

In one study, patients with the delta variant were 88% more likely to develop pneumonia compared to those with other strains of SARS-CoV-2.

Other researchers found that people infected with the delta variant were hospitalized 85% more often than for other variants, even when matched with patients of the same age, sex, socioeconomic status, and comorbidities.

A preprint study conducted in Canada determined that people with the delta variant were 120% more likely to require hospitalization, needed care in the ICU 287% more often, and died 137% more often than people who contracted other variants.

Lancet: Clinical and Virological Features of SARS-CoV-2 Variants of Concern: A Retrospective Cohort Study Comparing B.1.1.7 (Alpha), B.1.315 (Beta), and B.1.617.2 (Delta)

Lancet: SARS-CoV-2 Delta VOC in Scotland: Demographics, Risk of Hospital Admission, and Vaccine Effectiveness

MedRXiv: Progressive Increase in Virulence of Novel SARS-CoV-2 Variants in Ontario, Canada

In the US overall, hospital admission for Covid-19 for the week of August 11–17, 2021 increased by 14.2% over the previous week.

Florida reported a record 10,207 hospitalizations for Covid-19 on August 1, 2021 to the US Department of Health and Human Services. On August 20th, that number increased by 69% to 17,235, with 3,585 Covid patients in ICU beds.

Tampa General Hospital’s Covid patients more than doubled from 113 to 246 during August 1–20; its ICU had less than 10% availability during that entire period, rising from 51 to 103 people.

CDC Covid Data Tracker Weekly Review: Interpretive Summary for July 30, 2021 

Florida Statistics: What is Really Happening?

HHS Protect Data Hub: Hospital Utilization

Tampa General Hospital: Hospital Bed Availability for COVID-19 Patients

8. With other variants, older people and those in poor health were most likely to have a severe case or die. Is that still true with the delta variant?

According to the president of the Florida Hospital Association, this wave of Covid-19 due to the delta variant is dramatically different from what we previously experienced.

On August 2nd, Mary Mayhew stated, “In one of our hospitals, their average age now is 42 years old. They have 25-year-olds who are in intensive care, on ventilators…You have over 50% of our hospitalizations are between the ages of 25 and 55. It is a rapid increase, not only in hospitalizations, but in the deterioration. Sicker, sicker individuals. Again, pregnant women in our intensive care units. This is just dramatically different from what we saw last year… this is clearly ripping through the unvaccinated.”

She added that 96% of hospitalized Covid patients in Florida are unvaccinated and that younger people can no longer assume they are not at risk.

As of August 12th, the American Academy of Pediatrics (AAP) noted that severe cases of Covid-19 remain uncommon among children. However, whether due to more efficient transmission or increased severity of the delta variant, many more children are being hospitalized for Covid.

Due to concerns about long-term physical and mental health effects, the AAP recommends continued monitoring of children who test positive.

Florida Politics: Florida Hospital Association’s Mary Mayhew Says New COVID-19 Surge “Dramatically Different”

MedPage: Is Delta Also More Severe in Kids? Data are in Short Supply, but Hard-Hit Children’s Hospitals are Sounding Alarms

AAP: Children and COVID-19: A State-Level Data Report

9. I have been exposed to SARS-CoV-2 or tested positive in the last ten days. Is there a safe and effective treatment available? How can I access it?

Monoclonal antibodies are made in a lab to mimic those which occur naturally after infection with the delta variant of SARS-CoV-2.

An infusion given after exposure or when symptoms are still mild is 70% effective at preventing hospitalization or death.

People over the age of twelve who are at high risk of severe illness are eligible to receive this treatment at no cost. You can click here for additional information.

The current recommendation for monoclonal antibody recipients regarding vaccination is to wait for 90 days after the infusion or injection.

MedRxiv: REGEN-COV Antibody Cocktail Clinical Outcomes Study in Covid-19 Outpatients

CDC/IDSA: COVID-19 Clinician Call January 30, 2021

10. Can people who were infected with a different variant get Covid again?

Natural immunity from prior infection to prevent acquiring the delta variant appears to last about six months in people who develop antibodies. Given the highly infectious nature of this variant, reinfection is likely to occur after that without vaccination.

How do we know this?

  • The level of antibodies corresponds to the degree of protection against severe Covid
  • One-third of people who tested positive for SARS-CoV-2 and were sick showed no antibody response three weeks after they felt better. Some of them were severely ill. This happened most often in younger adults.
  • Less than half of people who recovered from Covid had detectable antibodies one year later
  • Eighty percent of reinfections occur in people without full vaccination.
  • Compared to people who were fully vaccinated, those who recovered from Covid had lower amounts of antibodies and a reduced T cell response one year after infection. The researchers strongly recommended that everyone with a natural infection get vaccinated.

In a study in Israel, people who recovered from Covid and received one dose of a vaccine cut their risk of reinfection in half.

Nature: Reduced Sensitivity of SARS-CoV-2 Variant Delta to Antibody Neutralization

Nature: Neutralizing Antibody Levels are Highly Predictive of Immune Protection from Symptomatic SARS-CoV-2 Infection

Emerg Inf Dis: Predictors of Nonseroconversion after SARS-CoV-2 Infection

MMWR: Reduced Risk of Reinfection with SARS-CoV-2 after COVID-19 Vaccination—Kentucky, May–June 2021

MedRxiv: SARS-COV2 Mutant-Specific T Cells and Neutralizing Antibodies after Vaccination and Up to 1 Year After Infection

MedRxiv: Comparing SARS-CoV-2 Natural Immunity to Vaccine-induced Immunity: Reinfections Compared to Breakthrough Infections

11. How well does one dose of an mRNA vaccine protect me from the delta variant compared to full vaccination?

For the Pfizer, Moderna, and AstraZeneca vaccines, one dose is only 30% effective against the delta variant. That rises to 88% after the second dose of an mRNA vaccine and gradually decreases.

A comparison of antibody levels in Moderna and Pfizer recipients revealed over twice the number of antibodies produced by the Moderna vaccine. This is likely due to the increased amount of mRNA in Moderna and the longer interval between doses.

Two doses of the AstraZeneca vaccine are initially 67% effective against the delta variant. One dose of Johnson & Johnson is 64% effective against moderate to severe disease.

If you have gotten only one dose and have been putting off finishing the series, it is very important to get that second shot. Remember, you will reach maximum immunity two weeks after the second shot.

Partially vaccinated people have a 56% greater risk of reinfection compared to fully vaccinated individuals. Only one-fifth of people who get Covid a second time are fully vaccinated.  

NEJM: Effectiveness of Covid-19 Vaccines against the B.1.617.2 (Delta) Variant

Science: Durability of mRNA-1273-Vaccine-Induced Antibodies Against SARS-CoV-2 Variants

JAMA: Comparison of SARS-CoV-2 Antibody Response Following Vaccination with BNT162b2 and mRNA-1273

BioRxiv: Comparison of Neutralizing Antibody Titers Elicited by mRNA and Adenoviral Vaccine against SARS-Cov-2 Variants

Nature: Reduced Sensitivity of SARS-CoV-2 Variant Delta to Antibody Neutralization

MMWR: New COVID-19 Cases and Hospitalizations Among Adults, by Vaccination Status—New York, May 3–July 25, 2021

12. How long does the protection from an mRNA vaccine last? Why are booster shots being recommended, and who should get one? If I got the Johnson & Johnson vaccine, should I get an mRNA booster?

So far, the vaccines appear to provide antibody protection for at least six months. The CDC now recommends not mixing vaccine brands, if possible.

Here is the rationale behind the need for an additional dose of vaccine:

MRNA vaccines protected three-fourths of fully vaccinated people in nursing homes during March 1st–May 9th. However, that dropped to just over half during June and July. Duration since vaccination and the increase in the proportion of cases due to the delta variant factor into this.

Over half of solid organ transplant recipients showed no antibody response after two shots of the Moderna vaccine. This is due to the immunosuppressive medications they must take. When those without antibodies got a third dose six weeks later, half of them developed antibodies.

A large study in Israel conducted prior to the delta variant’s arrival determined that the effectiveness of the Pfizer vaccine dropped from 90% in the general population to 71% among immunocompromised people. That is why the CDC is now recommending immediate booster shots for people in these categories:

  • Been receiving active treatment for cancer
  • Taking medicine to suppress the immune system after an organ transplant
  • Had a stem cell transplant within the last 2 years and suppressing the immune system
  • Have moderate or severe immunodeficiency due to diseases such as DiGeorge syndrome and Wiskott-Aldrich syndrome
  • Has an advanced or untreated HIV infection
  • Being treated with high-dose corticosteroids or other medications which may limit your immune response

Typically, a vaccination series has a longer interval between doses. For example, you would receive the second dose of a vaccine to prevent shingles two to six months after the first shot. That extended period enables a greater immune response to the second dose. Since the first dose of the mRNA vaccines protected only 30% of people, waiting longer was not feasible.

People who no longer showed an immune response six to eight months after the two-shot series received another dose of the Moderna vaccine which was modified to protect against the beta variant. Two weeks later, their antibody levels against the beta variant were at least as high as their immune response had been two weeks after full vaccination. Similar results should occur with a formula designed to protect against the delta variant.

While a third dose of the current Pfizer and Moderna vaccines appear to provide the necessary antibody boost, the companies are testing a modified version targeting the delta variant spike.

On September 17th, the FDA advisory panel recommended Emergency Use Authorization for the booster shots of the Pfizer/BioNTech COVID-19 vaccine (Comirnaty) for all individuals over the age of 65 and for anyone over the age of 15 at risk of severe Covid-19. They based this decision after reviewing the efficacy of booster shots in Israel.

The Johnson & Johnson vaccine appears to provide immunity for at least eight months. A trial with a second dose given two months after the first increased the protection to 94%. Whether a booster will be necessary is still being determined.

Science: Durability of mRNA-1273-Vaccine-Induced Antibodies Against SARS-CoV-2 Variants

CDC: Interchangeability of COVID-19 Vaccine Products

MMWR: Effectiveness of Pfizer-BioNTech and Moderna Vaccines in Preventing SARS-CoV-2 Infections Among Nursing Home Residents Before and During Widespread Circulation of the SARS-CoV-2  B.1.617.2 (Delta) Variant—National Healthcare Safety Network, March 1–August 1, 2021

JAMA: Antibody Response After a Third Dose of the mRNA-1273 SARS-CoV-2 Vaccine in Kidney Transplant Recipients with Minimal Serologic Response to 2 Doses

Clin Inf Dis: Effectiveness of the Two-Dose BNT162b2 Vaccine: Analysis of Real-World Data

CDC: COVID-19 Vaccines for Moderately to Severely Immunocompromised People

MedRxiv: Preliminary Analysis of Safety and Immunogenicity of a SARS-CoV-2 Variant Vaccine Booster

MedPage: What Happened to Variant-Specific COVID Vaccines? Are Vaccines Tailored to Beta or Delta Still Even Necessary?

MedPage: U.S. Adults to Be Offered COVID Booster Shots in September—New CDC Data Show Waning Immunity with mRNA Vaccines Amid Rise of Delta Strain

MedPage: FDA Panel Backs Pfizer Booster for Select Groups—Advisors Overwhelmingly Support Authorization but Shot Down Full Approval Bid

NEJM: Protection of BNT162b2 Vaccine Booster against Covid-19 in Israel

NEJM: Durable Humoral and Cellular Immune Responses 8 Months after Ad26.COV2.S Vaccination

MedPage: J & J Says Second Dose of Their COVID Vaccine Boosts Protection—Efficacy Data Promising but Confidence Intervals Wide

13. How effectively do the vaccines protect us from hospitalization or death?

As of September 20, 2021, 182,551,945 people in the United States had been fully vaccinated against COVID-19. During the same time, the CDC received reports of 19,136 patients with COVID-19 vaccine breakthrough infection at least two weeks after full vaccination who required hospitalization without dying or who died.

Most severe cases and deaths continue to occur in elderly people:

Total number of vaccine breakthrough infections reported to CDC: 19,136
Deaths
[Total=4,493]
Hospitalized, non-fatal
[Total=19,136]
Females1,977 (44%)7,035 (48%)
People aged ≥65 years3,882 (86%)10,136 (69%)
Asymptomatic or not COVID-related*839 (19%)2,912 (20%)

*Patient had no symptoms of COVID-19 or their hospitalization or death was not COVID-related

Using the same procedures as in the table in Question #1, I compared all hospitalizations and deaths for unvaccinated and vaccinated people in the US during July 26th through September 20th. The CDC stopped reporting breakthrough cases which do not result in hospitalization or death on May 1st.

Due to reports of missing data on vaccination status from states to the CDC regarding hospitalizations, I’ve made a worst-case assumption that the actual number may be twice the number reported and provided a range for that statistic:  

  • For every 42–81 hospitalizations, one person was fully vaccinated
  • For every 22 deaths, one person was fully vaccinated

Over the course of the entire pandemic, this means that at least 99.19% of fully vaccinated individuals had not been hospitalized, even without allowing for the two-week post-vaccination waiting period for full immunity to develop and without removing the unrelated hospitalizations. The likelihood of avoiding death was 99.75% after full vaccination.

As the proportion of cases due to the delta variant increased from 2% to 80% in New York, the effectiveness of full vaccination to prevent infection dropped from 92% to 80%. Nevertheless, the vaccines remained equally effective at preventing hospitalization (94.5% average). For each unvaccinated person who required hospitalization, there were twelve unvaccinated patients.

In the UK, 90% of adults have received at least one dose of a vaccine. That decreases the risk of hospitalization by 96%. However, slightly more than half of deaths have occurred in fully vaccinated people.

Compare an 80-year-old fully vaccinated man with a 45-year-old unvaccinated man. The risk of death from Covid doubles with every seven years of age. Dropping the likelihood of death 20 times by being vaccinated cannot offset increasing the risk of being 80 years old by 32 times.

CDC: COVID-19 Vaccine Breakthrough Case Investigation and Reporting

Politico: Holes in Reporting of Breakthrough Covid Cases Hamper CDC Response

CDC: Trends in the Number of COVID-19 Vaccinations in the US

MMWR: New COVID-19 Cases and Hospitalizations Among Adults, by Vaccination Status—New York, May 3–July 25, 2021

BMJ: Significant Proportions of People Admitted to Hospital, or Dying from Covid-19 in England are Vaccinated—This Doesn’t Mean the Vaccines Don’t Work

This series of memes adapted from an interview with a respiratory therapist gives an outstanding depiction of the difference vaccination makes:

Honolulu Emergency Management: The 7 Stages of Severe Covid-19

LA Times: On the Front Lines, Here’s What the Seven Stages of Severe Covid-19 Look Like

14. How risky is post-vaccination myocarditis for younger people? How does the risk of other vaccine side effects compare to the symptoms of Covid?

Concerns about myocarditis and pericarditis after vaccination have prevented many young men and women from getting vaccinated. For the mRNA vaccines, they have occurred at a rate of 12.6/million.

People who experience this side effect have chest pain within 2–3 days after receiving their second dose of an mRNA vaccine. Almost all cases remained mild, and the patients fully recovered.

However, young men who become infected with SARS-CoV-2 develop those conditions at a rate of 450/million. Infected young women experience them at a rate of 235/million. With the delta variant transmitting as easily as chickenpox, it is far safer to get vaccinated.

MedRxiv: Risk of Myocarditis from COVID-19 Infection in People Under Age 20: A Population-Based Analysis

Circulation: Myocarditis with COVID-19 mRNA Vaccines

MedPage Today: Post-Vax Myocarditis Playbook Has Mostly Worked So Far, Uncertainties Aside—Chest Pain is the Classic Warning Sign of Rare Phenomenon

A study of two million people in Israel compared the likelihood of experiencing a significant Pfizer vaccine-induced side effect to the risk of those same symptoms of Covid-19. Here are the results:

Compared to those infected with SARS-CoV-2, people vaccinated with two doses of the Pfizer vaccine were substantially protected against acute kidney injury, cardiac arrythmia, deep vein thrombosis, hemorrhagic stroke, heart attack, myocarditis, inflammation surrounding the heart, and blood clots in the lung.

While cases of shingles remained rare among individuals in that study, there was an increase in risk among those who received the vaccine.

The Radiological Society of North America recommends waiting 4–6 weeks after the final dose of an mRNA vaccine to undergo a routine mammogram, noting that swelling of lymph nodes in the armpit (lymphadenopathy) is a normal immune response that resolves with time.

This is a side effect which I experienced. While I was aware of a lump for a few weeks, it didn’t cause any problems. Nevertheless, I did mention it to the woman who did my mammogram. She then asked which arms had received the injections in case any swelling appeared in the scans.

NEJM: Safety of the BNT162b2 mRNA Covid-19 Vaccine in a Nationwide Setting

RSNA: Covid-19 Vaccine-Related Lymphadenopathy: What to Be Aware Of

15. Are mRNA vaccines safe for pregnant women and their babies?

Research comparing miscarriages, preterm births, and low birth weights as pregnancy outcomes for vaccinated women and women who were pregnant before the pandemic found no differences between them. No neonatal deaths occurred among vaccinated women.

Vaccinated women who breastfed their infants secreted Covid-specific antibodies in their milk for at least six weeks. That provided protection to their newborns.

On the other hand, pregnant women who become infected with SARS-CoV-2 are more likely to experience severe illness requiring hospitalization, breathing assistance, or ventilation. They also have increased risk of preterm delivery or death.

That is why the American College of Obstetrics and Gynecology enthusiastically recommends that all pregnant women receive vaccination.

Similar results occur with the AstraZeneca vaccine, and a second dose is recommended for women who become pregnant after starting the series. However, due to more research on pregnancy with the mRNA vaccines, Pfizer or Moderna are preferable for unvaccinated women.

NEJM: Preliminary Finding of mRNA Covid-19 Vaccine Safety in Pregnant Persons

JAMA: SARS-CoV-2–Specific Antibodies in Breast Milk After COVID-19 Vaccination of Breastfeeding Women

CDC: COVID-19 Vaccines While Pregnant or Breastfeeding

MedPage: “Alarming” Number of Pregnant Women Admitted to Alabama ICUs—The Trend Points to Just How Important It is for Pregnant Women to Get Vaccinated, Physicians Say

JAMA: Characteristics and Outcomes of Women with COVID-19 Giving Birth at US Academic Centers During the COVID-19 Pandemic

ACOG: ACOG and SMFM Recommend COVID-19 Vaccination for Pregnant Individuals

Royal College of Obstetricians and Gynaecologists: Covid-19 Vaccines, Pregnancy, and Breastfeeding

16. What about the risk of infertility?

Women may experience irregular menstrual cycles or changes in flow after vaccination or after having Covid-19. This is common for infections and immune system reactions and lasts for only a few months. The North American Society for Pediatric and Adolescent Gynecology recommends vaccination for adolescents and young adults.

A recent study confirmed that antibodies to the SARS-CoV-2 spike protein have no effect upon the implantation of an embryo or pregnancy development. In women, neither natural infection nor vaccination cause sterility.

Another study involving sperm counts in men found that sperm concentration and motility increased after the second vaccination. In contrast, research on men who contracted Covid-19 found reduced fertility and erectile dysfunction.

NASPAG Position Statement on COVID-19 Vaccines and Gynecologic Concerns in Adolescents and Young Adults

ASRM: New Study Reveals Covid Vaccine Does Not Cause Female Sterility

Royal College of Obstetricians and Gynaecologists: Covid-19 Vaccines, Pregnancy, and Breastfeeding

JAMA: Sperm Parameters Before and After COVID-19 mRNA Vaccination

The Conversation: COVID-19 Could Cause Male Infertility and Sexual Dysfunction—but Vaccines Do Not

17. How can I discuss this with people I love who are vaccine-hesitant?

Here is an explanation I gave to a friend who had been terrified about getting vaccinated until a mutual friend got Covid:

The day of our friend’s diagnosis, she got vaccinated but called me the next day because she wasn’t feeling great. I explained the vaccine to my friend using coral snakes and milk snakes to illustrate:

“Your immune system is encountering what it thinks is a coral snake and is rising up to kill it. If you’re not feeling good, it’s because your immune system is working to destroy a coral snake. Since there’s no genetic material there, it can’t reproduce, and it does not affect your DNA. Within a few days your liver clears out what’s left.

“Right now, you’re 30% protected from the delta variant. When another milk snake comes along, your immune system produces more protection to destroy what looks like the same threat.

“Two weeks after the second dose, when your immune system sees a coral snake, it’s prepared to overwhelm it before it can make you very sick. Based on what I’m seeing, most of the antibodies are in lymph nodes in your chest. That explains why fully vaccinated people who do get infected usually have mild cold symptoms. The virus gets neutralized before reaching your lungs.”

Nonvenomous Milk Snake Image via Wikimedia Commons
Venomous Coral Snake: Image via Wikimedia Commons

MedLine Plus: What are mRNA Vaccines and How Do They Work?

Ad Drug Deliv Rev: Controlling Timing and Location in Vaccines

Anchorage Daily News: You Got a Coronavirus Vaccine. But You Still Became Infected. How Did that Happen?

UAB: Three Things to Know about the Long-Term Side Effects of COVID Vaccines

18. What sources can I trust?

1) Health Data.Gov COVID-19 Community Profile Report – Updated every weekday

2) World Health Organization Situation Reports – These tend to be one day behind. Some nations are not keeping their information up to date:

3) Johns Hopkins UniversityJohns Hopkins Univ: Coronavirus Resource Center. Not recommended for Florida statistics as that state updates only once per week, is hiding deaths, and does not include any non-resident data.

4) MedPage Today MedPage Today: Covid -19 Updates

5) Investigation of SARS-CoV-2 Variants of Concern: Technical Briefings – for the UK

6) Redemptive History and Theology Covid-19 Information covers broader Covid-19 issues, including medical and theological perspectives

7) HHS Protect Public Data Hub Hospital Utilization by facility or by state

8) CDC: Covid-19 Integrated County View – transmission, cases, test positivity, deaths, hospital usage, % of vaccinated people, and a Social Vulnerability Index by county

9) Florida Statistics: What is Really Happening? – A review of Florida statistics showing what that state is trying to hide and how you can find the missing information.

Image via Wikimedia Commons