Dr. Shyam P Lohani

The world is in the midst of the worst surge in terms of cases even after two years of the COVID-19 pandemic despite widespread inoculation drive. Although many more people are or will be infected, there are signs that SARS-CoV-2 has changed in terms of its virulence as the Omicron variant is less likely to cause severe disease and there is still hope that the deaths will be much lower with this surge than previous ones.
The World Health Organisation (WHO) predicts that the next COVID-19 variant will be more contagious than Omicron with no guarantee that the future strains will be milder in causing severity. While seeing at the numbers of infections globally, millions of COVID-19 cases were reported last week setting a new global record for daily cases. A large number of cases is overwhelming healthcare systems in many countries throughout the world even though the Omicron variant seems to be less virulent in comparison to previous strains.

Virulence
The New Year witnessed a wave of Omicron cases, but the question still remains unanswered: will this be the last of the variants, or will a new "variant of concern" emerge in 2022? Biologists speculate that it would not be surprising that a troublesome new coronavirus variant develops this year. However, it is, at this time, difficult to predict how quickly the new variant would spread, how efficiently the virus would elude the human immune system, or whether it would cause more severe illness than the prior versions of the virus. Taking into consideration the current rate of coronavirus infection worldwide, and the mutation occurring on SARS-CoV-2, it has been predicted that new variants will emerge.

Owing to its highly transmissible nature and capacity to escape the immune defenses of vaccinated and even previously infected people, the omicron variant spread rapidly and prevailed over the delta variant quickly. The Omicron variant overtook the Delta strain and infected section of the populations that the latter could not readily infect.

Omicron has shown less likely to cause severe disease than prior variants as it grows more easily in the upper airways and less well in the lungs. Therefore, the variant spread more rapidly among people. The ability to infect rapidly may have made them to be less virulent. The infection due to Omicron so far has resulted in milder disease than previous variants; a massive increase in cases could still lead to a whopping increase in the rate of hospitalisations and deaths leading to further stress on healthcare systems that are already overstretched.

In the future, mutations that allow the ability to the virus to replicate extremely quickly, or escape the defenses of the antibodies that prevent it from entering cells, could also make the new variant more transmissible as well as likely to cause severe infection. Delta exhibited such a combination of characteristics as it spread more easily than all previous coronavirus variants and at the same time increased the risk of hospitalisation for unvaccinated people.

The protection developed against Delta and Omicron was found to be different in people who were infected for the first time, had a repeat infection, or had a repeat infection after vaccination. Those who were not immune and got COVID-19 for the first time when they were infected with Omicron did not have antibodies that could effectively neutralise other variants like Alpha, Beta, or Delta.
In those who got a repeat infection but were unvaccinated, the antibodies were somewhat better at neutralising other variants. The best antibody response was found in those who had Delta infection in the past as well as had completed vaccine doses and were infected by Omicron again. Antibodies in those people had a much superior ability to neutralise both variants, particularly Delta.

Hypotheses
It is difficult to predict the future of the SARS-CoV-2 pandemic. One critical question is where the next variant of concern will come from, since it may not mutate from the Omicron variant. Omicron was originated when Delta was predominant and also from a different branch of the coronavirus family tree than Delta. This makes it difficult in predicting the transmissibility and virulence of the upcoming variants as the next variant may originate from other variants than Omicron.

The hypothesis that the virus will slowly become less virulent failed in cases of HIV and Ebola that have not evolved to be less severe despite being around for decades while smallpox was another example of turning into less virulent prior to its eradication. Thus, the fate of the COVID-19 pandemic dwells in uncertainty. Another speculation is that the coronavirus would not be eradicated. Rather, it would become endemic and become the fifth coronavirus to permanently establish itself in humans, alongside four other seasonal coronaviruses that cause relatively mild colds and have been circulating in humans for decades.
There is a myth circulating widely in the media, and on social media that Omicron being less severe is a sign that the virus is weakening and evolving into a more mild illness. Therefore, even the vaccinated are advised to adhere to public health protective measures. After all, vaccines may not protect us from getting sick with coronavirus variants, but masks and other social distancing measures do.

(Prof. Lohani is the clinical director at the Nepal Drug and Poison information Center. lohanis@gmail.com)