Covid-19 virus still evolving, can continue to surprise us: Experts

The recent spike in flu cases has emerged as a new cause of concern after the Covid pandemic has been on a decreasing trajectory for the last few months.

Covid in the last two-three years overshadowed most respiratory viral infections. Since most of the restrictions have been lifted, wearing of masks and hand washing routine have taken a back seat. This year the flu has been spreading rapidly even before its expected seasonal rise in December and January.

Explaining the phenomenon, Dr Rajeev Jayadevan, Co-Chairman, National Covid Task Force of the Indian Medical Association (IMA), told IANS: "Still new to mankind, Covid virus is showing a continuous evolution in a short time period, throwing off multiple variants and recombinants. Through mutations, each successive generation is able to escape the human immune response generated to its previous version. After the Omicron era, the possibility of an all-new variant arriving is keeping scientists on the alert."

Jayadevan said influenza and RSV (respiratory syncytial virus) are other bugs that cause significant respiratory illnesses. They spread from person to person and respond to the same precautions that are followed against Covid-19.

Unlike Covid-19 which is caused by one virus, influenza is caused by a group of several viruses, which vary from year to year. Influenza viruses can live in birds as well as pigs, which helps increase their diversity, Jayadevan said.

He added: "RSV causes cold like symptoms, and is mostly harmless in older children. It can potentially cause severe illness in very young babies, who have tiny airways. There was a surge in RSV in many countries following the worldwide relaxation of pandemic restrictions."

There are several common cold-causing viruses, such as rhinovirus and adenoviruses as well as common cold-causing coronaviruses. Their mortality rate is low, and only basic preventive and supportive measures are needed.

Talking about the Indian ecosystem, Jayadevan said that another virus that causes concern is the dengue virus. Unable to directly spread from person-to-person, the dengue virus uses a vector or vehicle to travel from person-to-person: the Aedes mosquito. As the mosquito drinks an infected person's blood, viruses get inside the mosquito's gut and then travel to its salivary glands. When this mosquito bites a healthy person, the virus enters that person's body - through the mosquito's saliva.

"The most important aspect of dengue prevention is mosquito and larva control. The dengue Aedes mosquito bites during daytime and lays eggs in freshwater. Eliminating stagnant water, even small puddles in the locality is important", he said, adding that Hepatitis A and E are illnesses of the liver caused by viruses that spread easily in communities by the feco-oral route, causing jaundice. Fecally contaminated water is the medium of travel of the virus from person to person.

While talking about the Indian perspective of viruses outbreak, Dr Sharwari Dabhade Dua, Endocrinologist, Madhukar Rainbow Children's Hospital, said various flu-like influenza, enterovirus, rhinovirus and swine flu are rising in the country.

Tomato flu, which is caused by coxsackievirus, is also on the rise in the southern part of the country and is common in children, although adults, too, can be infected.

Dua added that camel flu or Middle Eastern Respiratory Syndrome which was first reported in the Middle East, is another strain of coronavirus. It infects camels too and can transmit to humans through aerosols. It has symptoms that are the same as those for flu, but can be severe in patients with underlying conditions such as diabetes, cancer, kidney and heart disease.

People coming back from the Middle East, with symptoms of flu, should be screened for it, Dua pointed out.