• New research shows that the COVID-19 mRNA vaccine provides immunity for at least 6 months.
• But because COVID-19 is so new, experts aren’t sure if immunity would decline after that.
• More research will need to be done to understand whether people need regular COVID-19 booster shots, experts say.

The COVID-19 vaccines made by Pfizer and Moderna are highly effective at preventing cases of COVID-19 under real-world conditions, and research suggests they should remain effective over time.

What remains unclear, however, is exactly how long the vaccine will prevent COVID-19, if booster shots may be needed, or whether the vaccine needs to be adjusted to fight emerging variants of the virus. or not.

In an April 2 ReportTrusted Source , the Centers for Disease Control and Prevention (CDC) studied nearly 4,000 vaccinated health care workers, first responders, and first responders. other essential and frontline workers.

They found that the messenger RNA (mRNA) vaccine developed by pharmaceutical companies Pfizer-BioNTech and Moderna prevented 80% of cases after the first dose and 90% after the second dose.

The station workers in the study were tested for COVID-19 weekly for 13 weeks.

The scarcity of positive COVID-19 tests among the study group suggests that the vaccine reduces the risk of transmission of SARS-CoV-2 from vaccinated individuals to others, the researchers said.

“Reducing the risk of possible infection in people with asymptomatic infections or in those days before the onset of symptoms is especially important for healthcare workers, first responders First responders and other frontline and essential workers because of their ability to transmit the virus are often in close contact with patients and the public,” the report notes.

“There is increasing evidence that… the likelihood of transmission of the virus after vaccination is very low,” said Dr. Susan Bailey, an allergist and immunologist and president of the American Medical Association. American faculty, told Healthline.

Protection lasts at least 6 months, possibly longer

Separately, Pfizer-BioNTech says that its ongoing phase 3 clinical trial of its mRNA vaccine shows that strong immunity persists in at least 6 months for vaccinated individuals.

The researchers found that the vaccine was 100% effective for severe disease as defined by the CDC and 95.3% for severe COVID-19 disease as defined by the Food and Drug Administration. Pharmaceuticals (FDA).

The vaccine was also found to be 100% effective against one of the major COVID-19 variants (known as B.1.351) currently circulating in South Africa.

A study including 12,000 vaccinated people also found “no serious safety concerns” with the Pfizer-BioNTech vaccine, the companies announced.

“The good news is that in Pfizer’s six-month condition report, immunity is still very strong and we anticipate that it will continue to stay strong,” Bailey said.

Bailey adds: “These people [trong nghiên cứu] been vaccinated for the longest time, and it tells us it can last at least 6 months. “But definitely longer than that – it doesn’t just drop after six months. I would worry if the efficiency is reduced by a third or half. “

The fact that the effectiveness of the COVID-19 vaccine remained largely unchanged throughout the study period is an indication that the protection is long-lasting.

Bailey notes that some vaccines, such as those for measles, mumps, and rubella, often offer lifelong immunity. Others, such as the flu vaccine, require a new shot every year.

“We don’t know which camps the COVID-19 vaccine will fall into,” she said. “If we needed a booster shot for COVID-19, we knew it would be easy to manufacture,” she added, thanks to the new mRNA technology.

Bailey said that the vaccines currently in use appear to be effective against the COVID-19 variants circulating in the United States. But as the coronavirus continues to mutate, variants may emerge with greater resistance to the drug.

“My prediction is that a situation where we need a booster shot in the future is not because the first dose of vaccine has run out, 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 of 100 cases of COVID-19 occurring in vaccinated people in Washington state has raised some alarm among the public.

But experts say 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 have been vaccinated, you still need to wear a mask, practice social distancing and wash your hands. to prevent the spread of COVID-19 to others who have not been vaccinated.” Dr. Umair A. Shah, Washington State Secretary of Health.

Written by Bob Curley on April 4, 2021- verified by Dana K. Cassell

SOURCE: https://www.healthline.com/health-news/how-long-does-immunity-from-covid-19-vaccination-last

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Translated by: Kimluan

Editing: Bao Ngan