Natural immunity against Covid infection could be stronger than vaccination when protecting against Delta variant: Recovered patients are 13 TIMES less likely to get infected than those who have Pfizer shots, Israeli study suggests
- A new study from Israel looked at thousands of people who had either been vaccinated against COVID-19 or had not been vaccinated but were previously infected
- Participants who received a double shot were 5.96 times more likely to get infected and 7.13 times more likely to experience symptoms
- After three months, the risk of infection was 13.06 times higher in immunized subjects and they were 27 times more likely to have symptoms
- Researchers say the study has many limitations, including the Indian ‘Delta’ variant that is dominant and that participants do not need to be tested
- Study does not discourage vaccination because unvaccinated people are still more likely to get infected with Covid or be hospitalized than vaccinated people
Natural immunity against previous COVID-19 infection may provide stronger protection against the Indian ‘Delta’ variant than immunity against full vaccination, a new study suggests.
Researchers compared people who had received two doses of the Pfizer-BioNTech COVID-19 vaccine with unvaccinated individuals who had recovered from the virus.
They found that participants with natural immunity were up to 13 times less likely to contract Covid than those who received two shots.
The team from Maccabi Healthcare and Tel Aviv University notes that their study — which has not yet been peer-reviewed — has many limitations, including the more transmissible Delta variant that was dominant at the time, requiring participants not to be tested. .
The study looks at breakthrough infections and doesn’t discourage vaccination with a recent report from the Centers for Disease Control and Prevention (CDC) showing that unvaccinated people still have five times as many COVID-19 infections and 29 times as many hospitalizations as those who have done so. had their shots.
Participants who received a double shot were 5.96 times more likely to become infected and 7.13 times more likely to experience symptoms, a new study finds.
After three months, the risk of infection was 13.06 times higher in immunized subjects and they were 27 times more likely to have symptoms
For the study, published on pre-print server medRxiv.org, the team looked at more than 800,000 people divided into three groups.
This included people who received both doses of the Pfizer vaccine and never had Covid, unvaccinated people who were previously infected, and people who had the virus and also received a single dose of the vaccine.
The research was conducted after the Delta variant became dominant in Israel, which has been shown to evade vaccines more easily than older strains.
Researchers found that fully vaccinated but people were much more likely to have a ‘breakthrough’ Covid infection than those with natural immunity to the disease.
Overall, participants who received a double shot were 5.96 times more likely to become infected and 7.13 times more likely to experience symptoms such as cough, fever and shortness of breath.
They also looked at the chance of vaccination after three months.
In this case, researchers found the odds of infections were 13.06 times higher in immunized individuals, and they were 27 times more likely to experience symptoms.
People who had recovered from the virus and had been vaccinated were even less likely to develop a breakthrough infection.
The team notes that there are several limitations. First, the study only examines the protection provided by the Pfizer vaccines and does not address any other approved vaccines or additional protection that a third dose provides.
Second, while the study controlled for factors such as age, gender and region of residence, there may have been differences in the behaviors of the groups — such as social distancing and mask-wearing — that were not taken into account.
dr. Andrew Croxford, an immunologist from the UK, also points out that someone who has previously tested positive for COVID-19 is unlikely to be retested for reinfection.
“If you’ve tested positive and isolated for weeks with significant disruption, how likely is it that you’ll be retested instead of thinking, ‘I’ve already had it, so it’s definitely something else’?” he tweeted.
‘Are people who refuse vaccination, or people with a previous infection, less likely to be tested?’
However, if the findings are confirmed by peer review, it could affect:
“This study showed that natural immunity provides long-lasting and stronger protection against infection, symptomatic disease and hospitalization caused by the Delta variant of SARS-CoV-2,” the authors wrote.
‘Individuals who were previously infected with SARS-CoV-2 and who received a single dose of the vaccine received extra protection against the Delta variant.’