NEW YORK – How long does covid-19 vaccine last?
Experts do not know yet, as they continue to study vaccinated people to determine when immunity could disappear. The effectiveness of vaccines against newer variants will also determine the need for additional injections, and when and how to administer them.
“We only have information about how long the vaccines have been studied,” said Deborah Fuller, a vaccine researcher at the University of Washington. “We need to study the vaccinated population and start seeing when they become vulnerable to the virus again.” .
At the moment, the study by the pharmaceutical company Pfizer indicates that the two-dose vaccine it developed with BioNTech remains extremely effective for at least six months and probably longer. Those who received Moderna also maintain visible levels of antibodies at six months after receiving the second dose of the drug.
But antibodies don’t explain everything. To fight intruders, such as viruses, our immune system has another line of defense called B and T cells, some of which can remain in the body long after the level of antibodies drops. If they encounter the same virus in the future, they may become active sooner.
Although they do not completely prevent the disease, they could help alleviate its severity. But at this point, the exact role that these “memory” cells could play against the coronavirus and for how long is unknown.
While current COVID-19 vaccines may be effective for about a year, they probably do not provide lifelong protection, such as measles, said Dr. Kathleen Neuzil, a vaccine expert at the University of Maryland.
“It will be somewhere in the middle of that wide range,” he said.
Variations are another reason why an additional injection may be needed.
Current vaccines are designed to target a specific protein in the coronavirus, said Mehul Suthar of the Emory Vaccine Center. If the virus moves enough over time, it may need to be updated to increase its effectiveness.
At present, vaccines seem to protect against more well-known variants, although somewhat less visible at first in South Africa.
If another injection proves necessary, a single dose may increase the protection of current vaccines or may contain the drug against one or more variants.
The need for a booster dose will depend, in part, on the success of the global vaccination campaign, the reduction of infections and the emergence of new variants.