CDC scientist says US is ‘far from close’ to collective immunity

The United States is “far from close” to achieving collective immunity against Covid, and more transmissible variants mean more people will need to be vaccinated to reach it, a CDC scientist said on Friday.

Collective immunity occurs when a sufficient number of people in a given community have antibodies against a specific disease, either through vaccination or through prior exposure to the virus. This makes it difficult to spread from person to person and even protects people who have no immunity.

“Currently, we know that the majority of the American population is not immune to SARS-CoV-2 and that variants can lead to an increase in that part of the population that is not immune,” said Adam MacNeil , epidemiologist at the Centers for Disease Control and Prevention.

To meet the herd immunity threshold while battling new, more contagious strains of the virus, a larger proportion of the population must be vaccinated, MacNeil said at a Food and Drug Administration meeting reviewing the request for Johnson & Johnson to authorize its Covid-19 vaccine in an emergency. use.

Scientists don’t believe immunity lasts forever. It weakens over time, which could worsen the epidemic as previously protected people become vulnerable to infection, MacNeil said.

His comments come a week after a Wall Street Journal opinion piece claimed the United States would be granted collective immunity by April.

While viral variants have shown a decrease in the effectiveness of a Covid vaccine in protecting against infection, vaccines have been shown to be effective in preventing serious illness and hospitalization against the most infectious strains.

A larger-scale vaccination would significantly slow the current trajectory of a highly contagious variant of Covid that was first identified in the UK as becoming the dominant viral strain in the US in March, MacNeil said.

He said the increase in immunization will be essential for the country to catch up.

“The vaccination has started and I hope this brings us closer to closing the immunity deficit in the herd.”