Previous COVID-19 infection protects against better delta mutants than Pfizer vaccine: study


According to an Israeli study, people who have previously recovered from COVID-19 have been observed to have better protection against delta variants of the CCP virus than those who received the Pfizer-BioNTech vaccine.

“This analysis showed that innate immunity provides longer lasting and stronger protection against infections, symptomatic diseases, and hospitalization due to delta mutations,” said researchers at McCabi Healthcare and Tel Aviv University. Said.

“This is the largest real-world observational study comparing the innate immunity obtained by previous SARS-CoV-2 infection with the vaccine-induced immunity provided by the BNT162b2 mRNA vaccine,” they added.

Innate immunity refers to the immunity that a person retains after recovering from the virus, in this case the CCP (Chinese Communist Party) virus (also known as the new coronavirus).

Preprints of studies that have not yet been peer-reviewed Published on medRxiv August 25th.

Researchers used data from Maccabi Healthcare Services, Israel’s second largest medical fund from March 1, 2020 to August 14, 2021. Unvaccinated individuals who have previously survived a COVID-19 attack. People who were previously infected and later vaccinated once.

Results were observed during the period from June 1st to August 14th, 2021. This corresponds to the time when the infectious delta mutant became the predominant CCP virus strain in Israel.

Researchers found that people who were completely vaccinated with the Pfizer vaccine were 13.06 times more likely to be infected with the delta variant of the CCP virus than those who had recovered from previous COVID-19 infections, and were at risk of symptomatic disease. Was found to be 27.02 times higher. These numbers apply when comparing the first vaccination or infection that occurred between January and February 2021.

When researchers compared all cases of previous infections from March 2020 to February 2021 with vaccinations from January to February 2021, the vaccinated cohort was infected with the delta variant. We found that the chances were 5.96 times higher and the risk of symptomatic disease was 7.13 times higher. For previously infected people.

The results suggest that the innate immunity gained from surviving a previous infection with COVID-19 may decline over time against the delta mutant, the authors write.

The authors said that those who were vaccinated were at higher risk of COVID-19-related hospitalization than those who were previously infected. They added that being over the age of 60 increases the risk of infection and hospitalization.

In another analysis, the authors compared both previously infected people with those who were previously infected and vaccinated once. They found that the single-vaccinated group was slightly less likely to be re-infected with the delta mutant, or 0.53 times less likely.

The authors suggest that the results “seem to gain additional protection from subsequent single-dose vaccine therapy” in previously infected people, but “could not show importance” in the cohort. Said that.

They acknowledged a number of restrictions, including the study observing only vaccine protection or innate immunity to delta variants. The study further observed only the protection of the Pfizer vaccine and did not examine the effects of third doses or boosters of other vaccines or Pfizer vaccines.

They also did not need to carry out COVID-19 tests such as PCR in Israel with protocols, so the actual number of asymptomatic infections is often that such individuals do not go to the test. He said it may be underestimated in this study.

The authors of the study also acknowledged that certain health behaviors, such as social distance and wearing masks, may play confounding roles in the study.

As the delta mutant began to spread around June, the Israeli Ministry of Health reported twice in early and late July that the vaccine was less effective against infection and slightly less protective against serious illness. bottom.

Scientists and institutions continue to investigate whether a third dose is needed. On August 24, the country expanded the target age for the third dose of Pfizer vaccine to over 30 years old.

With the continued spread of the Delta variant, Israel has imposed restrictions on indoor masks, meetings, strengthened rapid testing, and reinstated the “Green Pass” COVID-19 Vaccine Passport Program in late July. rice field.

Mimi Nguyen Lee

Mimi Nguyen Ly is an Australian-based reporter. She covers world news with a focus on US news. Contact her at [email protected].