COVID-19 vaccine insights: The news beyond the headlines

A large US study demonstrated that the risk of myocarditis for those who contract COVID-19 is 16 times higher than it is for those who are disease free.

Although the number of children affected by severe SARS-CoV-2 infection is less than the number of adults, there have been important trends observed in infection and hospitalization as different variants have arisen.⁵⁸ The Delta and Omicron variants have both been associated with a disturbing trend in the rate of hospitalization of pediatric patients, particularly from birth to 4 years—patients who were ineligible for vaccination at the time of the study.⁵⁸ Ultimately, these data, combined with multiple studies of vaccine effectiveness in this age group, have led to an emergency use authorization for the Pfizer-BioNTech vaccination in pediatric populations and a recommendation from the American Academy of Pediatrics that all children ages 6 months and older be vaccinated.^59,60

Immunocompromised patients. Patients broadly classified as immunocompromised have raised unique concerns. These patients have conditions such as malignancy, primary or secondary immunodeficiency, diabetes, and autoimmune disease; are taking certain classes of medication; or are of older age.⁶¹ Early in the pandemic, data showed that immunocompromised hosts could shed virus longer than hosts with an intact immune system—adding to their risk of transmitting SARS-CoV-2 and of viral adaptation for immune escape.⁶² Antibody response to vaccination was also less robust in this group.

There are limited data that demonstrate a short-lived reduction in risk of infection (in that study, Omicron was the prominent variant) with a fourth dose of an mRNA vaccine.⁶³ Based on these data and FDA approval, the CDC recommends (1) an additional third primary dose and (2) a second booster for people who are moderately or severely immunocompromised. For those ages 50 years or older, a second booster is now required for their vaccination to be considered up to date.^b

Predictions (or, why is a COVID-19 vaccine important?)

What does the future hold for our struggle with COVID-19? Perhaps we can learn lessons from the study of the 4 known seasonal coronaviruses, which cause the common cold and circulate annually.⁶⁴ First, only relative immunity is produced after infection with a seasonal coronavirus.⁶⁴ Studies of antibodies to seasonal coronaviruses seem to suggest that, although antibody titers remain high, correlation with decreased infection is lacking.⁶⁵ Second, a dominant strain or 2 emerges each season, probably as a result of genetic variation and selective pressure for immune escape from neutralizing antibodies or cellular immunity.

Boosters provide additional reduction in the risk of death and hospitalization, which led to a recommendation that all patients ≥ 5 years of age receive a booster.

The complex relationship among competing immune response duration, emergence of viral immune escape, increasing viral transmissibility, and societal viral source control (through vaccination, masking, distancing, testing, isolation, and treatment) widens the confidence bounds on our estimates of what the future holds. Late in 2020, the CDC began reporting wastewater surveillance data as a method for monitoring, and predicting changes in, community spread.⁶⁶ During Spring 2022, the CDC reported an increase in detection of SARS-CoV-2 from a third of wastewater sampling sites around the United States. This observation coincided with (1) appearance of still more transmissible BA.2 and, later, BA.2.12.1 variants and (2) general relaxing of masking and social distancing guidelines, following the decline of the Omicron variant.

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