While stressing that the Omicron variant infects both vaccinated and unvaccinated people worldwide, WHO Chief Scientist Dr Soumya Swaminathan said on Wednesday (December 29, 2021) that vaccines appear to be still proving to be effective because, despite the fact that the number of cases is increasing exponentially in many countries, the severity of the disease has not increased to a new level.
“As expected, T cell immunity holding up better against #Omicron. This will protect us against severe disease. Please get vaccinated if you have not,” said Swaminathan in a tweet on Wednesday. It may be noted that either vaccines or prior infections with COVID-19 trigger human T cell response.
Swaminathan also explained the factors concerning the same at a virtual press briefing of WHO on Wednesday. She said that vaccine effectiveness varies a little bit between vaccines though the majority of all of the WHO Emergency Use Listing vaccines actually have very high rates of protection against severe disease and death at least till the delta variant.
WHO Chief Scientist also stated that there are biological factors also that decide a vaccine’s effectiveness. “It includes age, underlying illnesses and we know and proved it with all the variants that the older you are the more the underlying illnesses and co-morbidities the more vulnerable you are to get the disease,” she said.
Referring to the third factor which decides the effectiveness of the vaccine, Swaminathan said, “It is the time since vaccination and the waning of the immunity and we know that there is some amount of meaning but again there is more waning for infection against infectious and that is why we are seeing a lot of breakthrough infections now especially with Omicron because Omicron does have the capacity to overcome pre-existing immunity, and needs higher levels anti-bodies and protection.”
Additionally, Swaminathan pointed that now the evidence on Omicron is just emerging and it would still be premature to conclude definitely but all of the lab studies are pointing towards a reduction in neutralisation capacity and also what it is clinically seen that people who have been vaccinated, people who have had prior infections are still getting breakthrough infections with Omicron.
“That is why the numbers that we are seeing around the world today are extremely high because these infections are occurring in both vaccinated and unvaccinated people. However, it appears that vaccines are proving to be still protective because even though the numbers are going up exponentially in many countries, the severity of the disease has not surged to a new level,” she added.
Swaminathan, while stressing that hospitalisations and even within hospitalised people the need for ventilation, the need for critical care that does not seem to be going up proportionately, said that this is a good sign and it is telling us that previous immunity is either due to vaccines or in some cases due to natural infection by the virus is providing some protection against the severe disease.
“And this is what we had expected because immunity, immune responses are much more than just neutralising antibodies,” she added.