As the coronavirus pandemic continues to affect the world, researchers are leaving no stone unturned in developing a clinically safe and effective vaccine to prevent COVID-19, the infection caused by the novel coronavirus.
Many vaccine candidates have been undergoing clinical trials, but researchers from the U.S. National Institutes of Health (NIH) propose that existing vaccines could offer temporary protection against the new coronavirus.
They highlighted the importance of repurposing vaccines, such as tuberculosis (TB) and polio vaccines, for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), or COVID-19, infection.
The researchers evaluated vaccines for polio and TB to see whether they can offer some protection against the new coronavirus.
The team believes that using old vaccines could curb the ongoing coronavirus pandemic, referring to evidence that the polio vaccine has reduced death rates and increased recovery from other viral infections, such as genital warts and the flu.
The researcher wrote in the journal Science, “An increasing body of evidence suggests that live attenuated vaccines can also induce broader protection against unrelated pathogens likely by inducing interferon and other innate immune mechanisms that are yet to be identified”
Studies have shown that the BCG vaccine (TB vaccine) and polio vaccines activate the innate immune system, resulting in enhanced responsiveness to other infections.
“Recent reports indicate that COVID-19 may result in suppressed innate immune responses (15),” the team added. “Therefore, stimulation by live attenuated vaccines could increase resistance to infection by the causal virus, severe acute respiratory syndrome–coronavirus 2 (SARS-CoV-2). Clinical studies of this hypothesis could begin immediately.”
However, the researchers propose the use of oral polio vaccine (OPV) over BCG to prevent or treat COVID-19 because both the poliovirus and the new coronavirus are positive-strand RNA viruses, meaning it is could induce a temporary immune response against COVID-19.
They also explained that using OPV is more beneficial because of its strong safety record, prolonged protection, easy availability, and affordability. Besides, OPV is generally safe with lower risks of complications than BCG.
The researchers noted, “If the results of RCTs with OPV are positive, OPV could be used to protect the most vulnerable populations. However, OPV would be most effective if the entire population of a country or region is immunized synchronously.”
“If proven to be effective against COVID-19, emergency immunization with live attenuated vaccines could be used for protection against other unrelated emerging pathogens,” they added.
Globally, the coronavirus has sickened more than 7.98 million people and killed over 435,000 so far. In the United States, public health officials have reported more than 2.1 million cases, with over 117,000 deaths. While vaccines are still undergoing trials, using old vaccines could help reduce the spread of the virus by providing temporary protection.
