People are waiting in line for vaccinations against coronavirus disease (COVID-19) at Martin Luther King Jr. Community Hospital in Willowbrook, Los Angeles, California, February 25, 2021.
Lucy Nicholson
The United States is “nowhere near” getting the herd’s immunity to Covid, and more transmissible options mean more people will need to be vaccinated to get it, a CDC scientist said on Friday.
Herd immunity occurs when enough people in a given community have antibodies against a specific disease, either through vaccination or previous exposure to the virus. This makes it difficult to spread from person to person and even protects people who have no immunity.
“We now know that the majority of the US population is not immune to SARS-CoV-2 and variants may increase this portion of the non-immune population,” said Adam MacNeil, an epidemiologist at the Centers for Disease Control and Prevention.
To reach the herd’s immunity threshold as it fights new strains of more contagious viruses, a larger proportion of the population needs to be vaccinated, MacNeil told a Food and Drug Administration meeting that examined Johnson & Johnson’s request to authorize Covid-19 vaccine for emergency use.
Scientists do not believe that immunity lasts forever. It weakens over time and could exacerbate the outbreak as previously protected people become vulnerable to infection, MacNeil said.
MacNeil’s comments come a week after an opinion piece in the Wall Street Journal claimed that the United States would obtain immunity from the herd by April.
While Covid variants have been shown to reduce the effectiveness of a Covid vaccine to protect against infections, vaccines have been shown to be effective in preventing severe disease and hospitalization against more infectious strains.
Intensified vaccination would substantially slow down the current trajectory of a highly contagious variant of Covid, first identified in the UK, becoming the dominant strain of the virus in the United States by March, MacNeil said.
MacNeil said increased vaccination will be essential for the country to reach the benchmark.
“Vaccination has begun and, hopefully, this brings us closer to filling the herd’s immune gap.”