Many vaccine clinical trials are underway to protect against COVID-19. Dr. Robert Gallo, co-discoverer that HIV is the cause of AIDS, recently spoke in favor of one study testing if oral polio vaccine (OPV) can prevent SARS-CoV-2 infections.
On the face of it, this idea seems far-fetched. SARS-CoV-2 and polio aren’t even related viruses. Nevertheless, there are good reasons to believe this may work.
Basically, the idea is that OPV can be used to activate the immune system before exposure to SARS-CoV-2. OPV is a live vaccine that temporarily grows in the gastrointestinal tract following vaccination.
When fighting a virus, even weakened viruses in vaccines, the immune system puts out all sorts of non-specific, protective chemicals to eliminate them. A good way to think about it is that the immune system is like a boxer. Upon entering the ring, the boxer puts his fists up and begins bobbing and weaving to avoid a hard hit while sizing up his opponent.
It’s hoped OPV can put the immune system in its defensive stance, so it can get in the first jabs should SARS-CoV-2 enter the scene. Given a head start, the immune system may be able to stop SARS-CoV-2 in its tracks, even before it can establish an infection.
Clues that this may work come from observations that mass OPV vaccination campaigns seem to decrease colds and other viral infections among those vaccinated.
The best evidence is from an OPV clinical trial conducted in the Soviet Union in the 1970s. In the trial, more than 60,000 children received OPV while 25,000 received placebo (sugar water). Unexpectedly, there was a 75 percent reduction in flu cases among the OPV group compared to the placebo group.
If it does work, the next question is the duration of protection. Likely, it will be only a few weeks to months. However, even weeks may be useful in tamping down local outbreaks just as relatively short lockdowns have been effective.
Historically, OPV contained three different strains. There’s a proposal to give each strain individually, spaced out over time, to extend the length of protection.
The vaccine costs pennies and is easy to give (many of you may remember it as the drops on a sugar cube). But, is it safe? Over 10 billion doses have been given around the world demonstrating it’s extremely safe.
Very rarely, the vaccine virus reverts to a dangerous form. This problem largely occurs in communities lacking good heard immunity. There’s a more expensive, killed polio vaccine used in the United States, but it doesn’t activate the immune system in the same way as the live virus vaccine.
The final question is whether it will work in people who have already been vaccinated against polio. Theoretically, yes. If vaccinated more than a couple years ago, the OPV virus will still grow in the gastrointestinal tract and stimulate the immune system.
Hopefully, OPV can help us knockout COVID-19.