The unprecedented speed at which the Omicron variant is spreading in countries that have high levels of testing, the number of people a single infected person can spread the virus to, and doubling time of less than three days are a loud warning that things can go out of control in a short while.
India witnessed the first death caused by the Omicron variant in a fully vaccinated person in Rajasthan on the last day of 2021. The 73-year-old man with comorbidities tested positive on December 15 and had been in hospital since then. Preliminary evidence from South Africa and the U.K. suggests that unlike in the case of the Delta variant, majority of people infected with Omicron, particularly those who are fully vaccinated, exhibit only mild disease; hospitalisation is relatively less among the vaccinated.
Huge percentage of the population in India got infected when the Delta variant raged through the country. Studies from other countries have shown that such people might enjoy the same level or even better protection from severe disease than fully vaccinated people. Hybrid immunity achieved through full vaccination in people who have been previously infected offers the highest level of protection against severe disease, as several studies undertaken outside India show.
With vaccination picking up speed after the second wave peaked in India, a significant percentage of the fully vaccinated might possess hybrid immunity. Even a single dose of an mRNA vaccine in previously infected people has been found to induce high level of hybrid immunity. If vaccination coverage with at least a single dose has already crossed 90% in those above 18 years, the rollout of vaccines for adolescents aged 15-17 years will widen the protective net.
Too early to reach conclusions
But immaterial of the protection conferred, it is too early to draw any conclusions about the virulence of the new variant even in fully vaccinated or naturally infected people. For instance, in the U.S., the first Omicron-related death was in an unvaccinated person who was previously infected.
The time-lag between infection and hospitalisation should be another reason why it is too early to pronounce any verdict on the virulence of the variant in India. Vulnerable population such as old people, immunocompromised, and people with comorbidities run a risk of suffering from severe disease despite their vaccination status.
The unprecedented speed at which the Omicron variant is spreading in countries that have high levels of testing, the number of people a single infected person can spread the virus to, and doubling time of less than three days are a loud warning that things can go out of control in a short while.
Pressure of health-care settings
Mild symptoms notwithstanding, the higher transmissibility of the virus can pose a severe threat to health-care settings as high number of infections within a short time can could lead to more people needing hospital care. Overwhelmed hospitals can make it harder to provide the much-needed care, leading to mounting deaths. The situation can become even more challenging when health-care settings suffer from staff shortage caused by increasing infections among health-care workers. Such a situation is already playing out in many hospitals across India.
India should learn from the hard lessons of the second wave and strictly adhere to COVID-appropriate behaviour and getting vaccinated. Getting misled by the mild-nature of the disease and throwing caution to the wind will be a dangerous gamble.
Science Chronicle 