Reaching true herd immunity to COVID is “probably unlikely”

COVID-19 mass vaccination site at the Lumenfield Event Center in Seattle. (Photo courtesy of Gov. Inslee / Twitter)

As more and more people are vaccinated with COVID-19, the concept of herd immunity continues to be talked about. Some health officials have previously stated that it may be difficult to reach true herd immunity, and Dr. Jeff Duchin, a public health officer in Seattle and King County, agrees.

State Health Department expects COVID vaccine doses to increase in April

Herd immunity, Duchin explained, Is a concept derived from animal health. That essentially means that the virus cannot spread effectively because the population has so much immunity.

“When one person is infected, the people around him become very immune due to either natural infection or vaccination, and the virus cannot infect the population,” he said.

So far, something like herd immunity has been achieved in the United States, but Duchin says there are pockets for unvaccinated people whose measles can still spread. Until recently, many people were vaccinated and could not be widely disseminated. In addition, the measles vaccine provides a high level of protection over the long term, Duchin says.

Many people have skipped vaccinations since the start of the COVID-19 pandemic. This pointed out that Duchin will be a real problem in the future. He encouraged expired children and himself, especially to catch up with routine immunizations for measles, mumps and rubella.

As long as COVID-19 herd immunity is achieved, Dr. Duchin believes that it is “probably unlikely” that the population has sufficient immunity to completely block the spread of the virus.

“But I think we can achieve a very meaningful level of population-level immunity so that our community is protected from hospitalization and death as a result of serious consequences, but the virus is transmitted from person to person. You won’t be able to stop it altogether, “he said.

There are several reasons he believes so. It starts with the fact that there are currently no vaccines for children.

“If 20% of the population is not vaccinated, herd immunity cannot be achieved,” he said.

“Second, very high levels of vaccination are needed to achieve herd immunity, which means the entire population,” he added.

Initially, it was thought that herd immunity could reach 70%, but due to the highly infectious mutants, higher levels (probably more than 80%) to prevent successful infection. Duchin says it is likely that vaccination will be needed. Reach true herd immunity.

“Another complex factor is that while vaccines are very effective in preventing serious illnesses, hospitalizations and even symptomatological diseases, we do not know exactly how effective they are in preventing infections. That’s what Duchin said. “Initial data suggests that they are very effective, but not 100%. That’s great news because it can reduce risk, but it can’t be ruled out.”

Duchin also pointed out that the duration of protection for the COVID-19 vaccine is still unknown.

“In order to maintain immunity, population reimmunization may be required,” he said. “Therefore, this is a very important logistics challenge, to maintain a very high proportion of the total population on an ongoing basis with high levels of vaccination.”

Finally, as the COVID-19 virus and its variants evolve, Duchin warns that it may become less susceptible to vaccine protection and may require the production and modification of new vaccines. doing. Duchin compared this situation with the flu vaccine. Influenza vaccines are being mutated and new vaccines are being developed to “meet the challenges of emerging viruses.”

Governor Inslee: Vaccination Eligibility in Washington Expands Again on March 31

“So, for some reason, I think true herd immunity, which means an absolute blockade of transmission in the population, will probably not occur,” he said. “But what is very realistic is that vaccination can achieve a sufficient level of immunity and protect the population from the most serious health effects of COVID-19, hospitalization, and death. And well. Hopefully, if people get enough vaccinations, the number of cases can be dramatically reduced. “

“This is somewhat similar to the situation of influenza, which has a vaccine that can prevent serious morbidity, mortality, and hospitalization each year, but with mild cases, infections, and future equilibrium with the virus. You have to live in a state, “he says. Added. “I think high levels of herd immunity are probably more realistic than true herd immunity.”