Opinion: Next, vaccinate those most likely to get infected

When the COVID-19 vaccination program began, vaccines were in short supply and demand was high. It was both ethical and practical to start by vaccinating frontline health workers and the elderly because these groups were at the highest risk of serious illness and death.

Credit: contributed

Credit: contributed

Once we met the initial demand from the highest-priority groups and our vaccine supply increased, additional high-risk groups became eligible, selected on their risk of getting seriously ill and dying. But while this approach to mass vaccination made sense at the beginning, demand is now low and opening vaccination to anyone who wants it in this next phase is insufficient.

A new tactic and tasks

Our new task is to identify those at highest risk of getting infected and infecting others and to target, engage, and vaccinate them. We need to add a more-strategic approach that links testing with vaccination and uses contact tracing and cluster identification to focus and guide vaccination efforts.

Credit: AP

Credit: AP

We have learned from prior pandemics and disease outbreaks that we need a strategic approach to coronavirus vaccination.

Mass vaccination by itself did not prove effective in eradicating smallpox or in containing Ebola. In 1796, an English physician, Edward Jenner, demonstrated that a vaccine was effective in preventing smallpox. For many years, health personnel tried to control the disease by vaccinating everyone they could reach. But it was not until countries started to use a more specific strategy for use of the vaccine that eradication became possible.

ID’ing and containing cases

In 1967 a “surveillance-containment” strategy, sometimes called “ring vaccination,” began to be used successfully in many endemic countries. “Surveillance” required identifying active cases of smallpox by training community members to find people with the classic symptoms of smallpox in their neighborhoods. “Containment” meant mobilizing vaccinators to track down people who might have been infected by those cases and stop transmission through quarantine and vaccination.

The surveillance-containment strategy did not require a high level of vaccination in the general population. Rather, focusing vaccination resources on people who were most likely to be infected interrupted transmission and eliminated smallpox in that region. Quickly vaccinating the contacts of a smallpox case and the contacts of the contacts of a case forms a protective “ring” around the case that may be geographical or epidemiological -- and prevents an outbreak.

In 1973, a nine-month effort adapted surveillance-containment to Indian conditions. That change in strategy resulted in India going from the highest smallpox incidence in decades, 48,833 cases in May 1974, to zero cases in the entire country by May 1975. Over the next three years this approach was successful in eradicating smallpox from every remaining country.

It took 200 years from development of the smallpox vaccine to the eradication of the disease. It took just three years once the right vaccination strategy was in place. Strategy was key. This lesson and the use of ring vaccination was applied as soon as the first Ebola vaccine was developed and helped contain the spread of that deadly disease.

An effective strategy

How can we combine intensive testing, contact tracing, and vaccination into a highly effective COVID-19 elimination strategy?

If we want to find the people who are at the leading edge of the COVID pandemic, we need to carefully look at cases and contacts identified by testing and contact tracing. Integrating vaccination into our COVID-19 testing and tracing programs will help target outbreaks and stop them before they occur.

We can see what is happening with nursing home clusters. As staff and residents are vaccinated, COVID-19 clusters in nursing homes have all but disappeared.

Clusters in non-congregate settings — restaurants, gyms, churches, factories — are more difficult to detect and contain and have seen a smaller, if any, impact from vaccination. But targeting vaccination to individuals at risk for infecting others in these settings is likely to be effective in preventing these outbreaks.

COVID is incredibly fast, so the ability of local health departments to get a vaccination team out to diverse locations like worksites will be crucial for controlling outbreaks.

Tests and opportunity

While some individuals at risk for spreading infection will be identified through contact tracing, others will be self-identified because they come for testing. They come for testing because they suspect that they have been infected or because testing is required before they can enter a setting where transmission may easily occur.

Offering vaccination to all who come for testing would have a broader impact than outbreak response because it reaches a huge number of unvaccinated people who are at high risk of infection.

Right now, we are ignoring millions of people each week who are seeking to be tested. The vast majority of them are, in fact, not infected with COVID-19, but are probably unvaccinated or partially vaccinated, and considering engaging or have engaged in social behaviors where COVID-19 could be spread.

There is no evidence to suggest that vaccinating someone who is infected poses a risk to that person. By asking everyone coming for a COVID test if they need to be vaccinated, and vaccinating them on the spot if they do, we can vaccinate people on the leading edge of the pandemic and stop transmission.

And in this phase, that is exactly what we need to do.

K. J. Seung is chief of strategy and policy for Massachusetts COVID Response at Partners In Health, an associate physician at Brigham and Women’s Hospital and assistant professor at Harvard Medical School. Mark Rosenberg is president emeritus of The Task Force for Global Health and retired as assistant surgeon general after working 20 years at the CDC. William Foege is a professor emeritus at Emory University.