Top Line

Protection against Kovid-19 infection begins to decrease just a few months after full vaccination, according to a new study. Study Led by researchers at Imperial College London, what scientists say underscores the need for a booster program to control COVID-19 infections as US regulators discuss whether to use Moderna and Johnson & Johnson’s vaccines When and when to offer additional shots of

important facts

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Breakthrough infection was more common in people who received their second dose of COVID-19 vaccine between three and six months earlier than in those who took their second dose within the past three months, the React study found.

Based on data from more than 100,000 swab tests taken between June 24 and July 12, researchers found evidence of stronger protection against infection for people who were fully vaccinated compared to people who were not vaccinated. , whose infection rate was 1.76%.

However, infection rates were higher (0.55%) among those who received the vaccine 3-6 months earlier than those who received the last dose within the previous three months (0.35%), the researchers suggested offering protection. Vaccination faded over time.

The researchers said the findings support the use of a booster vaccine to enhance immunity.

The study, which has not been peer-reviewed, did not examine vaccination to protect against serious illness, hospitalization, and death, a primary objective of vaccination that other studies suggest remains robust.

important quotes

Professor Paul Elliott, Director of the REACT Program said It is difficult to say what happens to immunity after three months. However, “it certainly shows an incentive for people to get their boosters when it’s available.”

what we don’t know

The study only looked at the Pfizer-BioNtech and AstraZeneca vaccines and did not look beyond the six-month mark. Other vaccines in use in the US, Moderna and Johnson & Johnson, also show signs of decline over time, and regulators are discussing the potential use of booster shots for these vaccines this week.


By measuring infections, the study provides better evidence of weakened immunity than many studies that support boosters, which generally estimate immunity with suggestive, though not absolute, proxies such as antibody levels in the blood. However, the researchers only looked at how many people tested positive for COVID-19 and did not account for whether those who tested positive had symptoms and if so, how severe they were. While preventing infection is important to control the spread of disease, an important purpose of vaccination is to prevent serious illness, hospitalization, and death. Experts agree that there is strong evidence that vaccines still achieve this and that premature booster campaigns threaten significant side effects in those who receive them.

main background

The US approved booster shots for immunocompromised people receiving Pfizer or Moderna Vaccine in August and announced plans to roll out the booster to the general public in September. The CDC pushed for the Pfizer shot to be used as a booster jab in seniors, high-risk workers and the medically vulnerable, a much broader approach than recommended by FDA experts, who recommended the use of the additional shot for adults in high blood pressure. Voted Against-Risk Jobs. the matter has taken hold Discussion among health officials and is set to rule this week as the FDA considers boosters for the J&J and Moderna vaccines. The rollout of booster shots has angered public health leaders around the world, who called the decision unfair given the vast disparities in vaccine access around the world. Several high-ranking FDA officials were co-authors of a paper Knife The medical journal argues against the need for boosters in the general public at this time, citing the lack of evidence that they are needed and the fact that scarce supplies would be better used to vaccinate those who need them. Compared to giving additional doses if not fully vaccinated. is already.

Scientific evidence does not support booster Covid shots, researchers warn – even for the delta version (Businesshala)

Booster Shots for COVID-19—The Debate Continues (pointed)

The immunity to the COVID vaccine is waning – how much does it matter? (Nature)