Pre-infection, vaccines provide the best protection from COVID

A new study comparing previous infections and vaccinations among people in California and New York concludes that taking shots is the safest way to prevent COVID-19.

the study Examination of infections in the summer and fall of 2021 found that those who were vaccinated and survived a COVID-19 attack were the most protective against the new coronavirus infection.

However, previously infected unvaccinated people were in the immediate vicinity. By fall, the more contagious delta mutants were inherited, but when boosters were not yet widespread, the group had a lower case rate than previously uninfected vaccinated people. ..

The Centers for Disease Control and Prevention, which published the study on Wednesday, pointed out some warnings to the study. Also, some outside experts were cautious about the findings and were wary of how they would be interpreted.

“The key message is that symptomatic COVID infections give rise to some immunity,” said immunologists. E. John Welly Of the University of Pennsylvania. “But it is much safer to get immunity from vaccination than to get infected.”

Vaccination has long been sought after, even after the case of COVID-19, as protection for both types eventually diminished.In addition, immunologists said there are too many unknowns to rely solely on past infections, especially old ones. Ali Elbedy At Washington University in St. Louis.

“There are so many variables out of control that it can’t be used as a way to say,’Oh, I’m infected and protected,'” Ellebedy said.

This study is consistent with a small cluster of studies that found that previously infected unvaccinated people were at lower risk of COVID-19 than previously uninfected vaccinated people. ..

The results of the new study make sense, he said. Christine Petersen, An epidemiologist at the University of Iowa. She said vaccines developed for previous coronavirus strains are likely to be increasingly ineffective against newer versions.

However, experts say that the effectiveness of the vaccine has simply declined over time in many people, how much it was involved in what happened to wearing masks and other behaviors, and so on. There are also some possible factors.

Another thing to consider: “not well vaccinated” is unlikely to be tested, and the study includes only laboratory-confirmed cases, Wheely said.

“In the unvaccinated group, reinfection may not be very high,” he said.

CDC officials have pointed out other restrictions. This study was conducted before the Omicron variant took over and before many Americans received booster immunization. Dramatically amplify protection By increasing the level of antibodies that fight the virus.

The analysis also did not include information about the severity of past infections. Nor was it able to address the risk of serious illness or death from COVID-19.

The authors of the study concluded that vaccination “continues to be the safest strategy” to prevent infection and that “all eligible individuals need to be up-to-date with COVID-19 vaccination.”

Researchers have investigated infectious diseases in California and New York, which make up about 18% of the US population. They also looked at COVID-19 hospitalization in California.

Overall, about 70% of adults in each state were vaccinated. An additional 5% have been vaccinated and were previously infected. A little less than 20% were not vaccinated. About 5% were unvaccinated but had been infected in the past.

Researchers investigated cases of COVID-19 from the end of May to mid-November and calculated the frequency of new infections in each group.Over time, vaccine-only protection Less and less impressive..

By early October, the case rates were as follows compared to previously unvaccinated people who had not been infected.

• Vaccinated but previously uninfected people are 6 times lower in California and 4.5 times lower in New York.

• One-29th in California and 1/15 in New York for those who have been infected but have never been vaccinated.

• Infected and vaccinated people are 32.5 times lower in California and 20 times lower in New York.

However, the researchers found that the difference in rates between these last two groups was not statistically significant.

Hospitalization data from California alone followed a similar pattern.

AP Medical Writer Lauran Neergaard contributed to this report.