Against Delta, past infections will protect more than the vaccine | International spread of corona virus

Against the delta variant, those who have not been vaccinated against Govt-19 before are better protected than those who have been vaccinated, according to a study by U.S. health officials released Wednesday. After all, the Centers for Disease Control and Prevention (CDC) underscores the “vaccine is the safest strategy” against the disease by releasing these data. In fact, infection can cause you serious problems, while vaccines have proven to be very safe and effective.




This study was conducted before booster doses became widely available and before the appearance of the Omigron variant, which now accounts for more than 99% of new cases in the United States. So it looks like the cards are currently being replaced. However, these results provide important components for a better analysis of the differences between vaccines or immunity acquired after infection.

The arrival of Delta changed the situation

Health officials in the states of New York and California investigated the cases from late May to November 2021. By the end of June the delta in the United States had become the majority. Throughout the study period, those who were not vaccinated or who had not been ill in the past were less well-protected. But before the Delta, those who were not vaccinated and those who were already vaccinated and those who were not infected with Govt-19 were better protected. After the arrival of Delta, the relationship turned upside down.

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In early October, the study analyzed those who were at risk of being affected by the delta, i.e. those who had not been vaccinated or infected in the past, compared the risk of catching the delta. Vaccinated individuals (but never infected) are six times less likely to catch it in California and five times less likely in New York. But this risk was further reduced for those who were previously infected (but not vaccinated): 29 in California and 15 in New York. In analyzing the risk of hospitalization this time only in California, the researchers found a similar reversal between the two periods.

How to explain it?

“It may be due to different stimuli of the immune response” caused by exposure to the actual virus or vaccine, the CDC explains. Prior to booster doses, the study authors added that this reversal was “consistent with a decrease in immunity induced by the vaccine in many populations.” The CDC notes that working in Delta in other countries has “proven to increase the safety of previously infected, vaccinated and non-vaccinated individuals compared to the vaccine”. They stressed the need for further research to examine the durability of the protection provided by the infection against each variant, including Omigran.

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