It’s been four and a half years since the COVID-19 pandemic first spread around the globe. The pandemic killed millions worldwide and disrupted everyone’s lives for months to years. In 2020, 2021, and 2022, COVID-19 was one of the top five causes of death in the U.S. and many other countries.
The virus is so contagious that nearly every human alive has either been infected by COVID-19, vaccinated against it, or both. Eighty percent of U.S. adults have received at least one dose of a COVID vaccine. COVID-19 antibody prevalence, which includes both vaccination and infection, exceeded 95 percent in fall 2022, a number so high that the CDC stopped reporting it at the end of 2022.
As our immune systems have gained experience against COVID-19, the severity of illness has drastically declined. Weekly deaths due to COVID have fallen roughly 30-fold from their 2020-2021 peak. But that doesn’t mean COVID-19 is harmless. Hospitalizations with COVID remain comparable to influenza, and deaths from COVID remain higher than influenza.
With that in mind, you may have heard that there are new COVID vaccines for the 2024-2025 season. The U.S. FDA approved Pfizer and Moderna formulations on August 22, 2024, and the doses should be widely available now. Current U.S. guidelines recommend annual COVID vaccination for all Americans age 6 months and up with rare exceptions, very similar to influenza vaccines.
Yet annual COVID shots have proven much less popular than flu shots. Only 22.5 percent of U.S. adults got a COVID vaccine during the 2023-2024 season, compared to 48.5 percent receiving the influenza vaccine.
Why is this? Well, the COVID vaccines have more short-term side effects than flu vaccines, with common phenomena including injection site pain, fever, fatigue, and muscle soreness. Severe side effects such as myocarditis (inflammation of the heart) are very rare but not zero. So, it’s reasonable for people to be less enthusiastic about annual COVID shots than about flu shots.
It’s also uncertain how much the COVID vaccines have maintained their efficacy over time. The initial placebo-controlled mRNA vaccine studies done in 2020 and early 2021 showed vaccine efficacy as high as 95 percent. But that was in a patient population with zero pre-existing immunity to COVID-19, a population that ceased to exist in 2022.
Since the end of the initial approval trials in 2021, there have been no new randomized controlled trials of COVID vaccine efficacy. The 2023-2024 and 2024-2025 updates of Pfizer/Moderna vaccines were approved based on bloodwork only, not on any clinical endpoint such as illness, hospitalization, or death. There have been observational vaccine effectiveness studies using the updated COVID boosters, but these are not randomized controlled trials and can be subject to selection bias and confounding.
Thus we can say for sure that each COVID shot boosts your COVID antibody levels for about 6 months, but we can’t know exactly how much that reduces your likelihood of getting sick compared to just keeping the antibodies you already have. This clinical efficacy is almost certainly higher than zero, but lower than the 95 percent measured in 2020-2021.
Given these facts, most of the world’s public health agencies have recommended that annual COVID vaccines be limited to people at high risk of severe illness. That includes the elderly, with age cutoffs of 65+ in France, the UK, and Canada, and 60+ in Germany. It also includes special populations such as residents of long-term care facilities, people with immunosuppression, people with other chronic diseases, and frontline healthcare workers. In a departure from these other countries, the U.S. government recommends COVID vaccination for everyone 6 months and older.
So, what’s my practice with regard to COVID vaccines? Well, I generally follow the most common practice around the world, which is to target COVID vaccinations to people at highest risk of severe COVID illness. Those who are elderly, live in a long-term care facility, or have an impaired immune system have the strongest probability of benefit from annual COVID vaccination. Those who are relatively young and healthy have a lower probability of benefit.
Regardless of your medical history, COVID vaccination is widely available in the U.S., and it is something you can discuss with your primary care provider. It’s best to talk to a healthcare professional who is familiar with your care, as you should never make a medical decision based only on something you read online.
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