SARS CoV-2, commonly known as the coronavirus, causes respiratory distress and pneumonia. It was first reported in late December 2019 in Wuhan, China. While Wuhan is still the epicentre, the disease has spread to over a dozen countries, including India, which has confirmed three infections so far. COVID-19 is the official name of the disease caused by SARS CoV-2.

As of February 21, the virus has infected around 75,000 people and killed some 2,200. The severity and the extent of the outbreak have led to much media attention, and speculation. Conspiracy theories about the possible origin of SARS CoV-2 have been floating around. A shoddy preprint by scientists at IIT Delhi suggesting the possibility of SARS CoV-2 having been weaponised with an HIV sequence was heavily criticised, precipitating its retraction.

Conspiracies and fake news around the coronavirus outbreak are hardly surprising, not least given the secretive and authoritative nature of the Chinese government. Among the many conspiracy theories, the most prominent claim it was originally designed as a bioweapon or that the outbreak was caused by accidental spillage of SARS CoV-2. Several non-Chinese scientists have published a statement in the Lancet denouncing these conspiracy theories, and showing solidarity with clinicians dealing with the disease. Still, unfounded claims are rife.

The counter to many of these conspiracy theories is hidden inside the virus genome. A genome is essentially the sum of all the genetic material – DNA and RNA – found in an organism. Think of the genome as a manual that helps in the assembly and functioning of an organism. When an organism like a virus reproduces, it makes a copy of the manual and passes it on to its offspring. Sometimes, in the process, a few letters of the manual are changed. These are mutations.

Now, what can we learn from the genome, and how?

First, we isolate the virus from a COVID-19 patient, and sequence its genome. Once we have the SARS CoV-2 genome, we compare it with thousands of other virus genomes. More similar the genomes, the more likely they have the same parental origin. The coronavirus that caused SARS in 2002-03 in China, for instance, is 79.5 percent similar to SARS CoV-2. The best match, at 96.2 percent similarity, is a coronavirus called RaTG13 which was sequenced from a bat in Wuhan. This helps us infer that SARS CoV-2 likely originated from a bat in Wuhan. Another virus found in pangolins is 99 percent similar to SARS CoV-2. This indicates that SARS CoV-2 likely originated in bats and infected humans via pangolins.

Is it a bioweapon?

As of February 21, at least 106 genome sequences of SARS CoV-2 are hosted on NextStrain, an open source bioinformatics platform. These genomes were taken from COVID-19 patients in 19 countries, including China. Analysing the differences among these genomes can tell us a great deal about the origin and transmission of this virus.

Trevor Bedford, a virologist at Fred Hutchinson Cancer Research Center in the US, compared the genomes of SARS CoV-2 and RaTG13, isolated from a bat. As noted earlier, they are 96.2 percent similar. This resemblance shows that these viruses had a common ancestor sometime between 25 and 65 years ago. To appreciate this inference, remember that the rate of mutations is surprisingly constant. As genomes are passed from one generation to the next, they keep accumulating mutations. More the mutations, the older the genome. This is how genomes are used to pinpoint timelines. Bedford’s analysis shows that the rate of mutations, of 14 percent, in the genome of RaTG13 and SARS CoV-2 is almost the same. Even places in the genome, the genes, where these mutations occur are quite similar in the two viruses.

This indicates that SARS CoV-2 has had the same evolutionary changes as its natural cousin. This wouldn’t have been the case if it were a bioweapon, or if a malicious gene or sequence were artificially added to SARS CoV-2 through genetic engineering. Many international experts have already ascertained this from a variety of genetic analyses.

A leak from some research lab?

The Wuhan Institute of Virology is just a few kilometres away from the Wuhan seafood market. Many politicians, even a few Chinese scientists, believe SARS CoV-2 was accidentally spilt from the Wuhan Institute of Virology. This is unlikely.

The institute, for one, houses China’s only Biosafety 4 laboratory. Biosafety 4 is a designation given to select labs which follow the highest precautionary standards, including airlocks, positive pressure suits, disinfecting chemical showers, separate ventilation and exhaust systems, effluent decontamination units. Only a Biosafety 4 lab can be used for dealing with pathogens such as Ebola, Nipah, Smallpox which are extremely contagious and don’t have medical cures yet. India has such a lab at NIV-ICMR, Pune, where samples of Nipah and SARS CoV-2 are sequenced for diagnosis. An accidental leak from such secure facilities is highly unlikely.

Bats are packed with viruses. Not all of them necessarily infect humans. Viral outbreaks such as SARS 2002-03 and COVID-19 happen when the genome of a bat virus mutates randomly. The mutations can sometimes enable it to infect pangolins and humans. SARS CoV-2 infects by binding to the ACE2 receptor in humans. This ability to bind is conferred by six mutations to a specific site on SARS CoV-2 genome. The virus isolated from pangolins has the same six mutations. This indicates the virus was likely transmitted via heavily trafficked and poached pangolins instead of some inadvertent lab release.

In a Twitter thread, Bedford points to the many pieces of evidence that debunk the accidental leak conspiracy. For instance, 585 environmental samples were collected from the Wuhan seafood market. At least 31 of the 33 samples that tested positive for SARS CoV-2 were collected from a western part of the market where wild animals are largely traded. We would not see such a point-specific concentration of positive samples if SARS CoV-2 was leaked from a lab.

Will it get worse?

Another persistent myth about SARS CoV-2 is that it may suddenly mutate and evolve to become more dangerous or spread more quickly. This is simply not how biology works. Mutations are not guided introspections, they are random darts in the dark. Most mutations, in fact, are harmless. You could, to use the earlier analogy, still read a manual if you flip a few characters in it. The mutations that increase virulence are very rare and accumulate over a very long period of time. Even when they do, they infrequently stick along. Nathan Grubaugh et al recently published an excellent review on this in the journal Nature.

The case fatality rate of COVID-19 is around two percent as of February 19. This means that out of every 100 infected patients, around two of them die. They are usually patients who are immunocompromised or old. Random mutations will likely not change this number. In the worst case scenario, if SARS CoV-2 becomes endemic, better surveillance, vaccines and newer antivirals would likely decrease the case fatality rate and disease burden.

So, what now?

Experts from WHO, the US Centers for Disease Control and Prevention, and other international organisations are actively studying and monitoring COVID-19. It is difficult to hide something as big as an accidental leak or planned outbreak from their watchful eyes. Also, an epidemic like MERS, SARS or Ebola is studied for years after they end. Biologists, epidemiologists, ecologists, and others study and reconstruct every aspect of such an outbreak. Malice, if any, will likely be unearthed by them.

China’s 2002-03 SARS outbreak killed 774 people and severely damaged its economy, and the world’s as well. The economic impact of the SARS CoV-2 outbreak will be massive. While China deals with the outbreak, the rest of us should stick with following the WHO recommendations and calling out the conspirators.

In the internet age, outbreaks such as COVID-19 inevitably come with a deluge of fake news and conspiracy theories. Many of the myths arise from xenophobia, as is evident from the stereotyping of and even racist attacks on Chinese people. Viruses don’t understand national borders. In the face of such global adversaries, thus, skepticism should not become speculation.