Why Covid vaccines may not prevent Omicron infection

The Permanent Secretary in the Ministry of Defence and Veteran Affairs, Ms Rossette Byengoma (left), receives her first dose of Covid-19 vaccine in Mbuya.  PHOTO/DAVID LUBOWA

What you need to know:

  • According to information from WHO, available studies suggest that for Omicron infection, there was a higher effectiveness two weeks after a Pfizer booster [third dose], which was slightly lower or comparable to that against Delta.
  • The agency said another study by South Africa researchers using private health insurance data reported reductions in vaccine effectiveness of the Pfizer vaccine against infection, and to a lesser degree against hospitalisation.

As Uganda records more Omicron cases, the World Health Organisation (WHO) has announced that preliminary investigations indicate a significant reduction in Covid-19 vaccine effectiveness against symptomatic disease from the variant.
“Results from England indicate a significant reduction in vaccine effectiveness against symptomatic disease for Omicron compared to Delta after two vaccine doses of either Pfizer or AstraZeneca- vaccines,” the report reads.

Uganda has detected 25 Omicron cases among incoming travellers who have been subjected to home-based care. 
But the Ministry of Health said it has not yet detected secondary cases in communities although the country is currently experiencing a spike in daily cases of infections. .
The report about the new variant and surge in cases is worrying health experts given that the country has only inoculated nine million of the targeted 22 million people since March, with the majority jabbed with AstraZeneca and some few with Pfizer.

Majority of those vaccinated have only received the first dose. The country is also inoculating people with Sinovac, Johnson & Johnson and Moderna vaccines.
 Dr Henry Kajumbula, the head of infection control and prevention at the government scientific advisory committee, told Daily Monitor that although the primary purpose of Covid-19 vaccine is preventing severe illness, the Covid-19 vaccine may give some protection against infection.

“There are many vaccines that protect recipients. This protection may not necessarily be against infection but against diseases. These include tetanus vaccine and diphtheria [for children]. Some vaccines are designed to protect against infection and others convert the toxins [that the infectious agent produces] that cause disease and so prevent illness,” he said.

He added: “For Covid-19 vaccine, there may be some protection against infection but the primary reason is to prevent severe disease.”
Prof Pontiano Kaleebu, the director of Uganda Virus Research Institute, told Daily Monitor earlier that in-country and foreign surveillance has unveiled increasing mutation in the coronavirus that may make the virus escape the protection from the vaccine.

Uganda is grappling with six variants of the coronavirus and Delta is still the dominant one, according to Prof Kaleebu. 
Omicron is a heavily mutated variant that has now spread to more than 77 countries, according to WHO.
Dr Kajumbula said: “The changes in the virus may affect the efficacy of the vaccine in preventing infection but the studies still show that they protect against the emerging variants [such as Omicron].”

“In various vaccines for Covid, one may need multiple doses for one to be protected. There is still much being learnt about the vaccine and Covid-19. The vaccine was approved under an emergency situation,” he added.
Since the outbreak of Covid-19 in Uganda in 2020, the virus has killed more than 3,274 people and infected 130,178.