Bengaluru: In the past few days, the theory of a possible leak from the Wuhan Institute of Virology, leading to the SARS-CoV-2 virus escaping and causing the Covid-19 pandemic, has been gaining steam. Those demanding investigations into the origins of the virus have been asking to investigate if instead of a natural zoonotic transmission, the SARS-CoV-2 virus was either being researched in a laboratory (lab) and leaked because of a biosecurity issue, or was engineered to be able to infect humans in the very lab.
While experts and virologists rule out the latter theory, some among them haven’t given a clean chit to the “lab leak” hypothesis, such as in the form of a researcher getting infected and then spreading the virus outside. However, while a growing number of voices are calling for an investigation of its possibility, many others in the scientific world remain unconvinced that the virus leaked because of a biosecurity failure.
Labs that research on pathogens are required to put in place levels of biosafety measures, the extent of which depends on the potential severity of infection caused by the pathogen being studied. Despite such precautions, accidental infections from the lab transmitted either through infected equipment or via those working at the labs are not unheard of.
ThePrint takes a look at some historic biosecurity accidents, how they occurred, and why scientists are concerned with both the origins of the virus, as well as the debate around it.
History of biosecurity
The scientific community is no stranger to accidental infections from viruses that researchers work on. A large majority of these tend to be lab acquired infections or LAI.
LAIs are caused by various pathogens such as bacteria, viruses, and parasites. The most common modes of transmission seem to be through contact via mucous membranes in body openings, respiration, consumption of a food or water borne pathogen, or being infected by a vector carrying a disease. Transmission can also occur through use of infected equipment, especially syringes.
The first LAI reportedly occurred in 1890, but it would be nearly a century before the connection between handling pathogens and human disease was well understood. This increasing awareness of transmission coincided with the time of the work of Louis Pasteur and Robert Koch, and the widespread acceptance of “germ theory”. The germ theory of disease in medicine is the theory that some diseases are caused because of infections by germs or microorganisms.
The first biosecurity measures in microbiology started to be properly implemented in the 1970s, primarily in higher income countries. These included personal protective equipment and personnel training for correct usage, as well as containment measures.
Apart from LAIs, there is also the risk from biotechnology that is factored into clinical research, and for which labs dealing with such work are well-equipped, given the risks.
The biggest risk comes from what is known as gain of function research, which cultivates microorganisms in secure environments in such a way as to purposefully provide them with a functional advantage, such as higher transmissibility or infectivity. This is anticipatory research, performed to understand where future diseases could come from and how existing microbes could mutate in the wild to suddenly become deadly.
Gain of function research is typically conducted in extremely controlled and secure environments.
One way to assess the security of such a controlled environment is through biosafety levels. These are pathogen protection level markers, which represent the extent of biocontainment precautions of an enclosed facility. While they are known in different countries as biosafety level (BSL), protection level (PL), or other names, the levels remain the same and number from one to four.
BSL-1 is suitable for work with well-understood pathogens that don’t infect healthy humans. Precautions include mandatory hand washing before entering and after exiting the lab. The lab does not require to be isolated from the main building. Staff are prohibited from eating or drinking while at the lab, and decontamination procedures with strict disposal are performed.
BSL-2 is more secure, and includes additional biosafety measures. These include training for personnel on the pathogens they handle, limited access to the lab, and procedures that can generate aerosols are contained in specialised equipment. Some pathogens suitable for BSL-2 investigations are HIV and Hepatitis group of viruses.
BSL-3 is suitable for work involving pathogens that can infect through the respiratory pathway. For increased protection, staff are immunised and vaccinated where possible. Regular PPE use extends to the entire body, and the laboratory must be isolated by multiple doors and pressure-controlled ventilation systems. to prevent the escape of a respiratory pathogen.
The SARS-CoV-2 virus is studied in BSL-3 labs, as are other coronaviruses, as well as the TB bacteria and the chikungunya virus.
BSL-4 labs deal with microbes that spread easily as aerosols. The disease such a pathogen causes is often fatal and there exists no treatment or vaccine for it, requiring careful isolation. These labs are equipped with biosafety cabinets within which all work is performed, where the researcher sits outside the glass cabinet and inserts their hand into gloved holes. No sharp objects are allowed, to prevent damage to the gloves.
Entry to the lab is by authorisation only, is via airlocks, and is recorded. All personnel pass through decontamination showers, from where they enter into an isolation room to remove their suit, which would be positively pressured to prevent outside air from coming in. This is then followed by a full body shower. All materials exiting the cabinet have to be soaked in disinfectant.
BSL-4 labs are used for work on the Ebola, Nipah, and Hendra viruses. Uncharacterised pathogens similar to BSL-4 pathogens, are worked upon here before their nature is determined. The only two centres studying the now-eradicated small pox virus, in Russia and US, are both BSL-4 labs.
Sample return missions to Earth from places that have water and could be habitable, such as Mars or Enceladus, have to first deposit their material in BSL-4 labs for purposes of planetary protection.
National Institute of Virology (Pune), CCMB-Hyderabad, and High Security Animal Disease Laboratory (Bhopal) are India’s three BSL-4 labs.
Before the now-established system, biosecurity incidences were not uncommon.
Laboratory workers becoming infected with the pathogens they were working on can be traced back in medical documentation to the early 1900s.
Most of the cases typically involved one or two people getting infected, sometimes by accidentally pricking themselves with infected needles. One of the most notable and unfortunate deaths in this manner was that of notable Australian microbiologist Dora Lush, who accidentally pricked her finger with a needle carrying a lethal strain of typhus in 1943.
The very last known small pox death, that of medical photographer Janet Parker in UK, occurred in 1978 after the virus leaked from the lab below her office. The same lab had been the source of another small pox leak, 12 years earlier.
However, there have been quite a few leaks of viruses that led to subsequent outbreaks or a large number of deaths. Spores of anthrax were accidentally released in Russia in 1979, leading to at least 66 deaths. A lab in Nigeria was responsible for “leaking” a number of viruses over 15 years between 1963 and 1977 that resulted in nearly a 1,000 infections and over 50 deaths. In China, brucellosis spread to over 6,000 residents just last year through contaminated gas from a biopharmaceutical factory, after expired disinfectants failed to remove bacteria from waste gas.
There have also been concerning outcomes from gain of function or ‘dual use’ research (research which has good scientific intentions, but great potential for harm), although these have affected the animals being tested upon, rather than any humans.
Mutated avian flu virus research is one of the most controversial subjects in the area.
A study managed to mutate the deadly H5N1 avian influenza virus to become transmissible in the air among ferrets — considered a close mimic to human systems — bringing to head growing concerns about the work into the virus in the US.
It first led to a moratorium on gain of function research in the US briefly in 2012, followed by a three-year freeze in funding.
However, there have hardly been any documented leaks of coronaviruses from laboratories, whether for dual use research or for therapeutics.
Lab leak investigation into Covid
The lab accident theory gained prominence after a group of eminent researchers wrote in the magazine Science seeking investigations into the origins of the virus, as there wasn’t enough evidence to rule out a lab leak.
A recent Wall Street Journal story that claimed researchers at the Wuhan Institute of Virology became sick with pneumonia in November of 2019, further added to the attention, but it has since been criticised for relying on unreliable sources.
The theory has gained prominence again as US President Joe Biden asked intelligence community to “redouble” its efforts into finding out the origin of the virus.
There have been many criticisms of the lab accident theory. Scientists have pointed out one of the more prominent ones, which is that Chinese scientists would have to have worked with the SARS-CoV-2 virus and made findings, but not published anything on it, even as they published on other coronaviruses.
While many scientists remain open to the possibility of a lab leak, and are asking to investigate to eliminate it, the scientific community itself is deeply divided over the nature of the controversy.
Many scientists worry that a claim like a leak from a lab requires strong evidence, and demands pushing for it sound like allegations. This also poses a diplomatic problem, as China has known to turn silent in the past when faced with unwanted pressure.
Investigations continue into the origins of the SARS-CoV-2 virus. However, being unable to determine the source or origin of a pathogen isn’t new. We still don’t know which animal the Ebola virus came from; the SARS-CoV-2 virus isn’t even the first virus we haven’t been able to trace, that spilled over to humans in recent times.
(Edited by Poulomi Banerjee)
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