People wait in line for vaccines 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” to achieving Covid’s collective immunity, and more communicable variants mean that even more people will need to be vaccinated to achieve it, a CDC scientist said on Friday.
Herd immunity occurs when a sufficient number of people in a given community have antibodies against a specific disease, either through vaccination or prior exposure to the virus. This makes transmission from person to person difficult and even protects people who have no immunity.
“We now know that the majority of the population in the United States is not immune to SARS-CoV-2 and variants can cause that portion of the population that is not immune to increase,” said Adam MacNeil, an epidemiologist at the Centers for Disease Control and Prevention.
To reach the limit of herd immunity while fighting new, more contagious virus strains, a larger proportion of the population needs to be vaccinated, said MacNeil at a Food and Drug Administration meeting reviewing Johnson & Johnson’s request to authorize his Covid- 19 for emergency use.
Scientists do not believe that immunity lasts forever. It weakens over time, and this can worsen the outbreak, as previously protected people become vulnerable to infection, said MacNeil.
MacNeil’s comments came a week after an opinion piece in the Wall Street Journal said the United States would achieve collective immunity in April.
Although Covid variants have been shown to decrease the effectiveness of a Covid vaccine to protect against infection, the vaccines have been shown to be effective in preventing serious diseases and hospitalization against the most infectious strains.
The increase in vaccination would substantially reduce the current trajectory of a highly contagious variant from Covid that was first identified in the UK as the dominant strain of viruses in the United States in March, said MacNeil.
MacNeil said the increase in vaccination will be critical for the country to reach the benchmark.
“Vaccination has started and, hopefully, this is moving us closer to filling the herd’s immunity gap.”