Are youngsters more vulnerable than elders in the second wave?

The age profile of Covid-19 active cases in Chennai shows that younger population or people less than 40 years account for the highest case loads. Of the 30,005 active cases as on May 6, 22 per cent are from 30-39 years age group against 15.24 per cent in 50-59 years group or 10.42 per cent in case of 60-69 years.

The trend is no different elsewhere. The latest data on the fresh Covid-19 cases, put out by various States, reveal a growing number of people in the younger age group with less than 40 years being more vulnerable to infection in the ongoing second wave compared to the older ones, who were the prime targets of the virus in the first wave.

BusinessLine spoke to leading virologists, infectious disease experts and academicians to understand this phenomenon and ascertain if the double mutant strain tends to affect youngsters more than elders. Is the decline in infection rate among elders due to the protection provided by the vaccine?

“The first two variants (Wuhan and D614G) of virus infected a proportion of Indians. People who were susceptible to easy infection were infected in the first wave and all others were spared. That included younger people also,” said Dr Jacob John, renowned virologist and former professor at CMC Vellore.

“The second wave is caused by many new variants and those who are infected have higher virus load. When these infectious people have higher virus load, the non-infected, non-immune people have a higher risk of getting infected. So, the proportion of youngsters who remained unaffected but susceptible were caught by the virus more than the immune older people. That alone explains the shift,” he added.

A dashboard on age-wise distribution of Covid-19 patients in India, put out by the National Centre for Disease Control (NCDC), shows 21.76 per cent of total confirmed cases in the country are from the age group of 31-40 years, while 21.70 per cent are in 21-30 years set. On the contrary, only 8.74 per cent of confirmed cases are from the 61-70 years bracket, while the 71-80 years set accounts for 3.56 per cent.

Anecdotal references

Gautam Menon, Professor of Physics and Biology at Ashoka University, and a professor at The Institute of Mathematical Sciences (IMSC), said that while there are anecdotal references about the shift in active caseloads from older to younger people, there is still no evidence to suggest a large-scale systematic shift.

“It is just that there are more patients overall and therefore the overall number of young people is also rising. The other thing is that what might have reduced the impact on older people is that the vaccination campaign has picked up and managed to protect a number of older people while some of them were already infected in the earlier round,” he added.

Dr Subramanian Swaminathan, Director - Infectious Diseases, Gleneagles Global Health City, Chennai, said while it is difficult to attribute one particular reason (for high infection among youngsters), it could be due to a combination of factors such as higher vaccine penetration among elders, high risk of virus exposure to younger ones who venture to meet livelihood challenges, and for the fact that a large number of vulnerable elders already being affected in the first wave itself.

“It may be possible that a new mutant is targeting the younger age group. It is also selection pressure when you start changing parameters for one group the other group becomes more interesting (for the virus),” said Swaminathan, adding: “The virus is also looking to survive and propagate itself so it will learn to adapt and pressure of adaptation depend on what we do.”

Virologist John, however, said the vaccine roll out is at an insignificantly low proportion to attribute it as the reason for decline in infection among the older population.

“If 10 per cent of the population is vaccinated with two doses, you could expect that to make a difference in epidemiology but not with one per cent vaccination,” he added.

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