New study says natural immunity to COVID reduced risk more than delta variant vaccines

Unvaccinated people who have previously contracted COVID-19 are better protected against the delta variant than those who have been vaccinated alone, according to a new study published Wednesday by a US health authority.

However, the Centers for Disease Control and Prevention (CDC) said in releasing the data that “vaccination remains the safest strategy” against the disease.

She also indicated that the disease exposes you to serious complications, while vaccines have been shown to be very safe and effective.

The study was conducted before doses of stimulants were widely available and before the emergence of the Omicron variant, which now accounts for more than 99 percent of new cases in the United States. So it is possible that the scales have shifted towards vaccination which is more effective than post-infection immunity.

However, the results published Wednesday provide important insights into the differences between vaccine-derived and post-infection immunity.

Health authorities studied cases in New York and California from late May to November 2021. The disease delta became the majority in the United States in late June.

During the entire study period, those who had not been vaccinated or contracted the disease in the past were by far the least protected.

But before Delta, vaccinated people who had never contracted COVID-19 were better protected than unvaccinated people who had already contracted the disease.

After delta was entered, the ratio was reversed.

Less dangerous for infected but unvaccinated people

The study analyzed the risk of developing delta compared to the risk of those most likely to have it, in other words, people who had not been vaccinated in early October or had been infected in the past.

Those who were vaccinated but not infected with COVID-19 were six times less likely in California and about five times less likely in New York.

But the risk was lower for individuals previously infected but not vaccinated: at 29 in California and 15 in New York.

When analyzing hospitalization risks, this time only in California, the researchers found a similar reversal between the two time periods.

The CDC explained that “this could be due to different triggers of the immune response” produced by encountering either the real virus or the vaccine.

The study authors added that the decline also “coincided with the onset of vaccine-induced decline in immunity in many people” before booster doses.

The CDC also noted that work on Delta in other countries “also demonstrated increased protection for previously infected individuals, vaccinated or unvaccinated, compared to vaccination alone.”

They emphasized that further studies are needed to examine the robustness of the protection offered by infection with each of the variants, including Omicron.

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