Covid is here to stay; no need to panic but take precautions, says PHFI’s Dr K Srinath Reddy

An infected person is not a case of Covid because Covid (patient) by the WHO definition is the one who has developed the illness. The fact that we have tested and found that somebody has been infected with SARS-CoV-2 virus does not automatically make that person a Covid case. We know that prior immunity, however acquired, is not likely to prevent an infection. It will most likely prevent a severe illness, and certainly it has helped to prevent deaths but it is not going to prevent an infection by the new virus variant. I think calling all of these as "cases" is, firstly, a misnomer. Second, we know that Covid is here to stay, and it's going to be an important respiratory virus among many other respiratory viruses, which continue to stay in our environment. Influenza viruses are an example and Covid will continue to change form.

Fortunately, we are still having the Omicron and its variants, which among all the lineages has turned out to be the least virulent, though it's quite infectious. So, seeing this sporadically come up again in the form of new variants and infect more people... but not necessarily causing severe disease, that's going to be a recurrent phenomenon unless the virus changes into a more dangerous form. The dangerous form is not likely to occur unless it actually acquires a part of the viral genome from another virus.

Antigenic drift is when the same viral genome continues to modify itself with slightly new forms but essentially retains the same character or characteristics and the same type of clinical features. But an antigenic shift occurs when it merges with the viral genome of another virus and then starts producing a totally new form of virus with a different genetic pattern and that can be dangerous.

Right now, we have no evidence that the SARS-CoV-2 virus, is actually going into the antigenic shift mode. At the moment, they are just changing their form in the antigenic drift mode and new variants are going to come up. And fortunately, they are still following the original Omicron pattern of being highly infectious but not highly virulent.

Thirty-seven people have died. Most of them had severe diseases or were people with co-morbidities. Do you think the government's response has been good enough or should measures such as contact tracing and wastewater surveillance be brought back?

People who are more likely to acquire a severe infection and die are the people with severe co-morbidities or who have a very severe dose of exposure to the virus, which their innate immunity or acquired immunity is unable to overcome. Certainly, masking will help if you are going to be in crowded places and if you are a mother who is treating a child with leukaemia, then you have to wear a mask and make sure there is adequate ventilation.

But whether all people require boosters is a moot question at the moment because there is really no reason to ask for boosters at the population level. But... Covid-appropriate behaviours are to be recommended, particularly to avoid crowds, and certainly, if you're moving in crowds to mask yourself, keep washing your hands. All the COVID appropriate behaviour recommendations of the past are still relevant and they not only help against Covid, they help against influenza and other respiratory viruses as well. So going in for boosters at this point in time is not really called for but all the other precautions certainly would be helpful for those who are at risk.

You just said a fourth dose or a booster is not important. Is a precautionary dose important ? Just about 20 percent of the population got the precautionary dose in the country.

Well, immunity is acquired by very many ways. First, you have your own innate immunity but acquired immunity comes from vaccines and from natural infection. It's very likely that even those people who did not get the booster dose have hybrid immunity, partly acquired from the vaccines, whether it's one dose or two doses. And, second, also through exposure to the virus, symptomatic or asymptomatic.

We must recognise that even if the antibody levels have come down, there are T-cells, particularly T helper cells, which still exist, and they can have a recall memory and can help, again, produce some of the antibodies. So we are not totally defenseless. I do not feel we need to have serious apprehensions about people who did not receive the third dose, at the moment. So ideally, they should have had it when they had the opportunity. But a lot of time has passed, and during this period, some of the immunity might have waned but some of the T-cell immunity would still be there for recall, and also it's possible that hybrid immunity has really extended its protective shield across the population.

What about the second dose? A lot of people didn't get the second dose either?

Ideally, they should have. If there's an opportunity to get it now, they should take it. But the simple message is that by now, most people would have acquired some level of hybrid immunity, and young people without comorbidities are not likely to be severely affected even if they are infected. So I don't think there needs to be a panic among them as well. But good public health advisories, when the government issues advisories based on clear cut evidence that certain vaccines are helpful under certain conditions, the population should take it.

What about those with serious co-morbidities? Would they need booster doses or is that not required as of now?

Well, ideally, if they have not had booster doses, they should get it if they are available but they should take precautions. Instead of just waiting for booster doses, wearing masks, avoiding crowds, ensuring that they take plenty of water and fruit and vegetables to build up their immunity, avoiding smoking, all of these are going to be important elements. Have good physical activity, which also is an immunity booster. So they should not sit quiet waiting for a booster policy to be announced.

Mask is a very good protection, if worn properly. It prevents the entry of the virus into the nose, and if you can actually ensure that you are avoiding a fair amount of danger to yourselves. The mouth and the eyes are also vulnerable. So frequently, drinking water, washing your mouth, washing your eyes, all this may be helpful.

Many people continue to report post-Covid complications, which we know as "long covid". What do we know about long covid studies?

Well, a number of studies have been carried out internationally as well as within India. We know that 'long covid' does affect people and affects even younger people. It is only partly related to the severity of the original infection but the virus does seem to have an impact. It's partly immunologically mediated, it appears. But I think, we still do not have clear-cut answers on how protective the vaccines are against long covid. There is some preliminary evidence that suggests that people who have been well vaccinated are unlikely to suffer severe, long covid but the treatments for it are still being tried out. The best way of avoiding long covid is to avoid the first infection itself.

There was talk of nasal vaccines, which were to be better at providing immunity and protecting us from future covid waves. How have they progressed and how different are they from the ones we got?

The nasal vaccine is something that produces mucosal immunity. It produces immunity in the nasal mucosa. So the virus finds it difficult even to enter and establish itself in the upper respiratory tract. The other vaccines cannot prevent that but they prevent it from producing a severe disease by attacking the lungs. So they protect you against severe illness and death, they don't protect you against infection, whereas nasal vaccines have the potential to do that by producing mucosal immunity. But so far, the development has been rather slow, and right now, globally, the trials have not really taken place to establish how effective they are. In fact, the natural infection with the circulating non-virulent virus variant is probably going to be serving very well as both a nasal vaccine and a systemic vaccine.

Is there a seasonality to the virus?

Well, people are looking for seasonality globally. The seasonality can never be established at a single season because seasons have different calendar periods across the world. So unless we watch this pattern for a little longer time, we will not really be able to comment about seasonality. Now, you have so much of travel within the country from one geographic and environmental zone to another. You have so much of travel internationally between one country and another country, therefore viruses, which emerge in one place can easily be carried to other places. It's not like viruses are sitting and just watching the calendar. They're traveling with people.