- New research shows that mRNA COVID-19 vaccines provide immunity for at least 6 months.
- But since COVID-19 is so new, experts aren’t sure if immunity will wane afterward.
- Experts say more research needs to be done to understand whether people need regular booster shots for COVID-19.
The COVID-19 vaccines produced by Pfizer and Moderna are highly effective at preventing COVID-19 cases in real-life conditions, and research shows that they must maintain their effectiveness over time.
What remains unclear, however, is exactly how long the vaccines will prevent COVID-19, whether booster shots may be needed on the way or whether vaccines need to be modified to combat emerging variants of the virus.
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They found that the messenger RNA (mRNA) vaccines developed by the pharmaceutical companies Pfizer-BioNTech and Moderna occurred 80 percent of cases after the first dose and 90 percent after the second dose.
The front-line workers in the study were tested for COVID-19 every week for 13 weeks.
Researchers said the lack of positive COVID-19 tests in the study group indicates that the vaccines reduce the risk of transmission of SARS-CoV-2 from vaccinated individuals to others.
“Reducing the risk of transmissible infections, which can occur in individuals with an asymptomatic infection or in individuals several days before symptoms start, is especially important for healthcare professionals, first responders and other key and frontline workers, given their potential to reduce virus through frequent close contact with patients and the public, ”the report said.
“There is growing evidence that … transmission of the virus after vaccination is likely to be very low,” said Dr. Susan Bailey, an allergist and immunologist and president of the American Medical Association, at Healthline.
Separately, Pfizer-BioNTech said the ongoing phase 3 clinical trial of its mRNA vaccine demonstrates that strong immunization lasts for at least 6 months in vaccinated individuals.
Researchers found that the vaccine was 100 percent effective against serious illness as defined by the CDC, and 95.3 percent effective against severe COVID-19 as defined by the Food and Drug Administration (FDA).
The vaccine was also found to be 100 percent effective against one of the main COVID-19 variants (known as B.1.351) currently widely circulating in South Africa.
A study involving 12,000 vaccinated individuals also found “no serious safety concerns” with the Pfizer-BioNTech vaccine, the companies announced.
“The good news is that in Pfizer’s 6-month status report, immunity remains very strong, and we expect it to remain strong,” said Bailey.
“These people [in the study] have had the vaccine the longest, and it tells us it will take at least 6 months, ”added Bailey. “But it’s definitely longer than that – it won’t just go away after six months. I would have been concerned if efficacy had dropped by a third or a half. ”
The fact that the effectiveness of the COVID-19 vaccine has remained virtually unchanged over the study period is an indication that protection will be durable.
Bailey noted that some vaccines, such as those for measles, mumps, and rubella, generally confer lifelong immunity. Others, like the flu vaccine, need a new injection every year.
“We don’t know which camp the COVID-19 vaccine will fall into,” she said. “If we need a booster shot for COVID-19, we know it will be easy to produce” thanks to the new mRNA technology, she added.
Bailey said the vaccines in use now appear to be effective against the COVID-19 variants circulating in the United States. But as the coronavirus continues to mutate, variants may emerge that are more resistant.
“My prediction is that a situation where we will need a booster shot in the future is not because the first dose of vaccine has been taken, but because a new variant could emerge,” she said.
As noted in the study, vaccines do not completely eliminate the risk of developing COVID-19.
A recent report on 100 COVID-19 cases that occurred in vaccinated people in Washington State caused some public unrest.
But experts said such “breakthrough” cases are expected and represent only a fraction of the more than 1 million Washington residents who have been vaccinated.
“Finding evidence of breakthrough vaccine cases reminds us that even if you are vaccinated, you should still wear a mask, socialize, and wash your hands to avoid spreading COVID-19 to others who aren’t. have been vaccinated, ”said Dr. Umair A. Shah, Washington State Secretary of Health.