The World Health Organisation (WHO) has recently reported a case of MERS-CoV (Middle Eastern Respiratory Syndrome Coronavirus) in a 28-year-old from Abu Dhabi, who did not have a history of contact with animals such as dromedary camels, sheep and goats known to transmit the infection to humans. Neither did he have contact with someone who had the infection. This, however, should not be a cause of concern, says Dr Ekta Gupta, professor of virology at the Institute of Liver and Biliary Sciences, New Delhi.

According to the WHO, 108 healthcare workers from two hospitals, who came in contact with the patient, were tested for the infection and found to be negative. None of them got the disease in the 14 days that they were monitored.

MERS is caused by a cousin of the Sars-CoV-2 virus that led to the Covid-19 pandemic. Since the first case in 2012, there have only been 2,604 laboratory confirmed cases in the world. Of those confirmed to have the infection, 936 people died, putting the case fatality ratio at 36 per cent.

Is there a need to be worried?

Not really. Isolated cases such as this one are not uncommon. MERS is a zoonotic disease that is known to have jumped to humans from dromedary camels. It is a respiratory infection like Covid-19, so the first few cases are usually transmitted from animals such as camels or other reservoirs like sheep and goats to humans.

In this case, perhaps the infected person came in contact with one such animal and did not know or remember. A bigger concern is when the infection passes from humans to humans — what is referred to as secondary cases. No secondary cases being detected so far is a good sign that the spread is in check. Once it moves to humans, the likelihood of it travelling farther becomes higher.

Since MERS belongs to the same family of viruses that causes Covid-19, is there a likelihood of MERS becoming a pandemic?

It doesn’t seem like it. MERS has been around since 2012 and it is still seen mostly in Saudi Arabia and Middle Eastern countries. Although during the initial outbreak, the infection was reported from 27 countries around the world, it has been restricted thereafter.

The mortality is high, but it doesn’t seem to spread very quickly. Covid-19 became a global pandemic because of its ability to infect several people quickly, sometimes even before the initial case realised that they had the infection.

Can the Covid-19 vaccine protect us from MERS?

There might be some cross reactivity between Sars-CoV-2 and MERS, but we do not know. The research to see whether that is the case hasn’t really happened in India since we haven’t seen any MERS cases.

If there have only been a few cases of MERS since 2012, why are people concerned about the virus?

When researchers look for pathogens that might cause pandemics in the future, viruses are one of the most important categories. Among them RNA viruses are like the entire family of coronaviruses, including those that cause SARS, Covid-19 and MERS. They are also one of the fastest changing. The more a virus replicates and mutates, the more it becomes capable of transmitting faster or causing more severe disease. Whether a virus causes a pandemic depends a lot on the transmissibility (ability to infect others), virulence (severity of disease), and attack rate (proportion of at-risk people who actually get the infection).

Respiratory viruses have a pandemic potential. This is not just because many are RNA viruses but also because they can easily be transmitted by coughing, sneezing and sometimes even through aerosolized particles suspended in the air.

What can be done to protect against future pandemic?

One, we are now adopting the one-health approach. This enables us to keep an eye not only on infections happening in humans but also on infections that may jump from animals to humans.

Two, the government has set up many viral research and diagnostic laboratories across the country that will help in detecting quickly any emerging infection.

Three, we are adopting a symptom-wise testing approach. What this means is that if a person comes in with respiratory symptoms like shortness of breath, their sample can be sent for a respiratory panel test. Such a symptom-based panel will test for many viruses, bacteria or other pathogens that cause symptoms like fever, breathing difficulty or diarrhoea.

Four, many researchers are now looking to develop pan-coronavirus vaccines. With SARS and Sars-CoV-2 having caused a pandemic, there is a lot of research happening in this field. And, such a vaccine is likely to protect against all these infections.

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