How Long Is Immunity From COVID Vaccine Lasting?
If you are fully vaccinated against COVID-19, you are probably breathing a sigh of relief. But how long can you expect this feeling to last? The CDC has yet to venture on its website to suggest the duration of post-vaccination immunity, but several studies have given us some clues.
For now, this is mostly good news. A letter from the Vaccine Research Group to the New England Journal of Medicine in April (you can think of these letters as mini-studies) found that humans still had strong protection six months after receiving the second dose of Moderna vaccine. The team writes: “Although the antibody titers and assays that best correlate with vaccine efficacy are not known at this time, the antibodies that were elicited by mRNA-1273 persisted for 6 months after the second dose, as detected by three separate serological tests.” Pfizer also announced in April that it found people who received the Pfizer vaccine still have strong protection six months after taking the second dose.
These research results do not mean that the protection only lasts six months, it just still, at the six-month checkpoint, the immunity is still strong. Remember, both vaccines were authorized in December, so the vaccine has only been on the market for six months. Even subjects in vaccine trials, on average, had follow-up data of just two months at the time the vaccine manufacturers applied for approval, so they are only slightly ahead of the rest of us. (The Johnson & Johnson vaccine is launching on a later schedule than the others, as its trials ended a few months after the other two.)
Trials using booster injections have already begun, but so far it looks like it will be at least a year before anyone needs them , and possibly longer. Immunity is a tricky thing, and scientists have yet to develop a test that can distinguish a person who is protected from COVID-19 from someone who is still susceptible. We will likely learn more in the coming months, but now we can probably be confident that our vaccines are at least six months old, perhaps at least a year, and maybe longer.