- A research study claims that previous exposure to the coronavirus can increase the likelihood of side effects after receiving a COVID-19 vaccine.
- Common coronavirus vaccine side effects include fever, headache, chills, and fatigue.
- One volunteer who participated in Pfizer’s Phase 3 clinical trial said the side effects felt like a “severe hangover.”
- When COVID side effects manifest, they typically go away after 24-hours.
One of the great things about the COVID-19 vaccines from Pfizer and Moderna — aside from their 95% efficacy rate — is that both vaccines haven’t been found to cause severe side effects. In clinical trials that involved tens of thousands of people, the only side effects reported by volunteers included fever, headache, fatigue, and chills. Further, when these side effects did manifest, they typically went away within 24 hours.
While there’s no way to predict who will experience side effects from the vaccine and who won’t, the CDC notes that older people are more likely to experience the symptoms listed above. Meanwhile, a new research study — which has yet to be peer-reviewed — suggests that people who previously contracted COVID-19 are more likely, on average, to experience side effects.
The study found that vaccine recipients who already had COVID had a “significantly higher frequency” of side effects than individuals with no prior exposure to the coronavirus. Incidentally, side effects after the first dose — which typically involves soreness and swelling around the arm — were distributed equally amongst all subjects. Recall that the more serious symptoms above typically manifest only after the second dose is administered.
The study further suggests that people who already had COVID-19 and recovered might only need a single vaccine dose to attain a significant level of immunity. If the theory is in fact accurate, it would be helpful to the extent that it would free up vaccine supply for others.
These observations are in line with the first vaccine dose serving as boost in naturally infected individuals providing a rationale for updating vaccine recommendations to considering a single vaccine dose to be sufficient to reach immunity. Using quantitative serological assays that measure antibodies to the spike protein could be used to screen individuals prior to vaccination if the infection history is unknown. Such policies would allow not only expanding limited vaccine supply but also limit the reactogenicity experienced by COVID-19 survivors.
As to how the current vaccination effort in the US is going, the CDC yesterday said that 26.4 million people have been vaccinated thus far. Of that group, 6.1 million people have received both vaccine doses.
One encouraging data point is that the US is currently administering an average of 1.3 million vaccine doses per day. President Biden, meanwhile, is working hard to boost that figure up to 1.5 million per day. If the US can reach and sustain a 1.5 million vaccination rate, Dr. Fauci believes we will be able to achieve herd immunity this summer.