A study published in the journal one more showed how countries using oral polio vaccine have a lower incidence of coronavirus disease (COVID-19) than those using inactivated polio vaccine – suggesting that oral polio vaccines either cause severe acute respiratory syndrome Can prevent infection with coronavirus 2 (SARS-CoV). 2) Slowing down transmission at the individual level or in the community.
Study: Use of oral polio vaccine and incidence of COVID-19 in the world. Image credit: frank60/Shutterstock
Even though vaccines against SARS-CoV-2, a causative agent of the ongoing COVID-19 pandemic, are our current best weapon, there are currently limitations in the production and delivery of these specific vaccines in many resource-limited settings.
However, studies have shown that other vaccines that are already widespread may also provide some degree of protection against SARS-CoV-2. More specifically, vaccines that use a live, but attenuated pathogen, can stimulate the innate immune system and provide at least temporary protection against many other different viruses.
Some examples of such vaccines are Bacillus Calmette-Guerin (BCG) against tuberculosis, and even oral vaccines against poliomyelitis, a disabling and potentially fatal disease affecting children. Previous studies have shown that this vaccine can exert a protective effect against influenza by reducing deaths by four times without any notable side effects.
Is the same valid for COVID-19? A research group coordinated by Dr Robert Charles Gallo, an eminent US researcher, hypothesized that countries using the oral polio vaccine have a lower cumulative number of COVID-19 cases per 100,000 population than those using only the inactivated polio vaccine .
Distribution of COVID-19 incidence rates in each country. The fill color represents the cumulative number of cases diagnosed with the disease per 100,000 population. The color of the countries border shows the type of polio vaccine used in each country. Complete data was not available for the gray areas. Made from Natural Earth (https://www.naturalearthdata.com/).
a multidisciplinary approach
It was an ecological study based on the cumulative number of COVID-19 cases in each country, the country’s population (with population density), the mean age of residents in the country, and life expectancy at birth.
The researchers also took into account the human development index (HDI), gross domestic product (GDP) per capita and the type of vaccine against poliomyelitis used in each country. Although the number of COVID-19 tests performed per day in each country would be a better metric than the HDI, the authors noted that this information was inaccessible in many countries.
In addition, a tightness index has also been obtained, which is a composite metric that indicates how strict the lockdown measures and restrictions were in each country. Accordingly, the average value for each country has been used for analysis purposes.
Finally, the World Health Organization Global Polio Eradication Initiative (WHO GPEI) provides data on the type of polio vaccine in each country. At the same time, world maps were produced with the help of the Natural Earth public domain dataset.
Low rates of COVID-19 in countries with oral polio vaccine
Briefly, oral polio vaccine use by a specific country was shown to be an independent predictor for a low rate of diagnosed/reported COVID-19 cases per 100,000 population. Although this did not prove a causal relationship, the effects were somewhat significant.
More specifically, countries using inactivated polio vaccine had an estimated average of 4970 cases per 100,000 population, compared to the pooled mean of 1580 cases for those using the oral polio vaccine.
Although it is difficult to account for the effects of lockdowns and travel restrictions due to policy changes over time, the mean hardness index did not differ significantly between countries using oral polio vaccines and inactivated polio vaccines. The same was valid for population density.
setting the agenda for further research and policy
This study shows that the oral polio vaccine can either prevent SARS-CoV-2 infection at the individual level or fundamentally inhibit viral transmission (and subsequent disease development) at the community level.
“An important consideration is whether the use of the oral polio vaccine against COVID-19 is a viable option, as many countries have attempted to generate rare but severe vaccine-associated paralytic polio cases and to reduce the generation of the circulating vaccine. Its use has been discontinued due to potential to trigger poliovirus-derived poliovirus”, caution study authors.
“Therefore, re-introduction of the oral polio vaccine into such countries should be considered very carefully, and before doing so, direct clinical evidence of its effectiveness (and for that matter, other live vaccines) should be prepared.” should be done”, he adds. one more paper.
Nevertheless, the potential for the use of conventional or newer oral polio vaccines to reduce COVID-19 is tentative, and this is in line with the conventional antigen-specific vaccines we already have in common with the creation of a novel class of specific vaccines. can open the door.