Bats not to blame for COVID outbreak, Israeli researchers say

Bats are not to blame for the outbreak of the COVID-19 pandemic, Israeli researchers from Tel Aviv University found more than two-and-a-half years after the first cases of COVID-19 were identified.

The TAU researchers pointed out that blaming bats “was not based on sufficient, compelling scientific proof and caused unnecessary stress and confusion worldwide.”

Researchers published their findings in the respected iScience Journal under the title, “Revising the paradigm: Are bats really pathogen reservoirs or do they possess an efficient immune system?”  

The study – led by Dr. Maya Weinberg, who works under Professor Yossi Yovel, head of Tel Aviv University’s Sagol School of Neuroscience – focused on bats and diseases, but did not proffer an alternative origin of the virus. 

Weinberg said a general misconception about bats harboring contagious diseases helped to proliferate the idea that bats had passed on COVID-19.

“In general, bats are mistakenly conceived of as reservoirs of many contagious diseases, only due to their being serologically positive – in other words, in possession of antibodies, which means that bats have survived the disease and developed an immune response,” Weinberg said. “After that, they overcame the virus altogether and disengaged from it; hence, they are no longer its carriers.” 

“Nevertheless, in many cases, a virus similar to a human pathogen is liable to be found in bats; however, it is not pathogenic to humans, and is not sufficient to use bats as a reservoir,” she said.

The Israeli research team checked its findings for more than 100 viruses, of which bats generally have been considered carriers.

“In order to examine the overall situation, we conducted a meta-analysis of the literature and checked the findings for over 100 viruses for which bats are considered potential reservoirs – such as Ebola, SARS and COVID. We found that in a considerable number of cases (48%), this claim was based on the incidence of antibodies or PCR tests, rather than actual isolation of identical viruses. Moreover, many of the reported findings are not convincing,” Weinberg said.

She explained that the isolation of a virus to an animal is not enough to see the animal as a reservoir for that virus.

“The mere isolation of a virus is not enough to see an animal as a reservoir, since a minimum number of index cases is required in which the virus is isolated in order to be considered a reservoir animal – as well as the existence of an established path of transmission,” she said. “Furthermore, the very detection of a particular virus in bats does not necessarily ensure further infection, and other biological, ecological and anthropogenic conditions must exist in order for such an event to occur.”

Overall, the research team concluded that their study raised “serious doubts” as to whether bats were the origin of the COVID-19 pandemic. 

“The comprehensive study we’ve conducted raises serious doubts regarding the possibility of bats being the origin of the COVID-19 outbreak,” Weinberg said. “The findings give rise to the opposite perspective, according to which we must study in-depth the immunological anti-viral capabilities of bats, and thus obtain new and effective means of coping, in humanity’s struggle against contagious disease, aging and cancer.”

Although the findings might have exonerated bats, the researchers said, “Until now, two years after the pandemic first broke out, we still do not know for sure what the exact origin of the COVID-19 variant is.”