At the beginning of this year, it was great to watch the precipitous decline of Covid-19 cases across the U.S. Unfortunately, the numbers plateaued in late February and are inching up in tandem with hospitalizations. This is despite the fact that over 200 million doses of vaccines have been given in the U.S. thus far, and more Americans are vaccinated every day.
In response to this rise, a recent Washington Post article noted that “Michigan officials have pleaded with the White House for more vaccine doses,” but the administration decided to “stick to allocations based on state populations,” and that “vaccine aren’t rapid response tools for outbreaks.”
It may be instructive to note that, a) vaccines have indeed been used as rapid response tools for outbreaks, and b) when the current plan is not working (i.e. trying to vaccinate the entire population), then it is useful to step back and reconsider the strategy. Here is where history could help us.What History Can Teach Us
In 1966, the World Health Organization (WHO) launched a massive, global program to eliminate the dreaded scourge of smallpox. At the time, there were still millions of cases occurring worldwide. By 1980, smallpox disease was eliminated from the face of the earth. The virus was locked up in two repositories – one in the U.S. and one in the former Soviet Union - and it hasn’t escaped since.
How did this happen? Initially, the WHO was using a similar vaccination strategy to what the U.S. is using currently – they were trying to vaccinate large populations in every country where smallpox occurred. Surprisingly, despite high vaccination rates, outbreaks still occurred. In Nigeria, while trying to deal with an outbreak of smallpox and a critical shortage of smallpox vaccine, Dr. William Foege, the Nigeria country manager for the WHO’s program, made a decision that would change the course of history. He launched a strategy known as surveillance and containment, which is also known as “ring vaccination.”
With this approach, rather than trying to vaccinate everyone, they instead focused on finding where the cases were occurring and used their limited vaccine supplies to vaccinate contacts of known cases, followed by contacts of the contacts. This proved highly effective in reducing disease, and it was adopted by the eradication effort worldwide. The end result was elimination of smallpox from humans. Dr. Foege’s reputation in the pantheon of public health leaders was sealed. He would later go on to lead the Centers for Disease Control and Prevention and other public health institutions.
This same ring vaccination strategy has been used more recently to fight Ebola virus during the massive West Africa outbreak in 2014-16. It proved highly effective, and it has since been used as a tool in subsequent outbreaks.
Could this strategy work for Covid-19? I don’t know. There are some key differences with smallpox that made it ideal for ring vaccination compared to Covid-19. When someone has smallpox, you don’t have to be a rocket scientist to recognize the characteristic skin lesions. Villagers could report possible cases without even having a confirmatory blood test. Not so with Covid-19, since the virus could be confused with multiple other respiratory illnesses, and even some cases are asymptomatic. But this challenge could be overcome with rapid diagnostics and rapid case reporting.
The other advantage in favor of ring vaccination for smallpox was someone could be exposed to smallpox and still be protected with the vaccine, if they received the vaccine within a few days. This would be a greater challenge with Covid-19, because the time period from exposure to illness (the “incubation period”) of a few days is much shorter than that of smallpox. Because of this, it would take some thought on how to put this concept into action with some variation on the smallpox and Ebola experiences.