Omicron Update: Three Times More Contagious, but Is It Actually a Milder Form of COVID-19?

The first major study of the effects of the Omicron variant of COVID-19 has been released by South Africa’s largest private health insurer, showing that while the variant seems to be causing milder symptoms in the country’s young people, vaccinations appear to be less effective against the new strain, a strain that is proving to be extremely contagious—the new variant now accounts for 90 percent of cases in South Africa—two factors that have the potential to render any reprieve that milder symptoms might provide—provided they are actually milder to begin with—entirely moot.

While still preliminary and pending peer review, the study, conducted by South African private health insurer Discovery Health, examined the test results of more than 211,000 positive COVID-19 test results that were taken between November 15 and December 7, that included about 78,000 results that were attributed to Omicron. The new strain is starting to show resistance to vaccines, with two doses of Pfizer-BioNTech’s shot only providing 33 percent effectiveness against overall infection (bear in mind this number takes into account cases that show no symptoms), but that those two doses still provided 70 percent protection against hospitalization during South Africa’s recent surge in cases. Although this is down from the same shot’s 93 percent effectiveness versus the deadly Delta strain, it is still well above the World Health Organization’s 50 percent requirement for a vaccine to be considered effective.

The study also found that there is a “significantly higher” risk of reinfection amongst people that had recovered from a previous infection from earlier variants, with former Delta patients having a 40 percent chance of being reinfected, rising to 60 percent for those that have recovered from a Beta-variant infection and 73 percent for original strain Alpha patients.

Unfortunately, children involved in the study had a 20 percent higher risk of hospitalization from Omicron compared to South Africa’s first wave. “Notwithstanding the fact that children continue to show a very low incidence of severe complications following COVID-19, Discovery Health’s data indicates that children under age 18 have a 20% higher risk of admission for complications of COVID-19 when infected with Omicron,” according to Shirley Collie, Chief Health Analytics Actuary at Discovery Health. Collie cautions that while the data is still preliminary, this trend is in-line with a similar increase in pediatric admissions during the country’s third, Delta-fueled wave. But despite the increase, the overall risk for young children is still low. “Children were 51% less likely to test positive for COVID-19 relative to adults in the Omicron period and, overall, the risk of children being admitted to hospital for COVID-19 complications remains low,” Collie explains.

Although Discovery Health’s press release did not provide a reproductive value for the new variant’s spread in South African communities, the new strain “accounts for over 90% of new infections in South Africa, and has displaced the formerly dominant Delta variant,” according to the company’s CEO, Dr. Ryan Noach. Like with other strains, Omicron’s transmissibility will vary from region to region, affected by factors such as social distancing, PPE use and the vaccination status of the local population; however, health experts are concerned that this variant may result in not a new wave, but rather a “tsunami” of new cases, as described by Scotland’s First Minister Nicola Sturgeon.

“I don’t think we’ve seen anything like omicron in this pandemic yet,” explains Sarah Otto, an expert in modeling and evolutionary biology with Canada’s University of British Columbia. “It’s capable of taking over in a matter of a few weeks.” Modeling by Ontario’s COVID-19 Science Advisory Table estimates that despite a 76 percent vaccination rate amongst the province’s population, Omicron will have a reproductive value of 4.01, making it more than three times more transmissible than all other variants combined, with the number of cases expected to double every three days; this means that for every one person infected with Omicron, they can be expected to spread the disease to four other people before the disease has run its course for that individual.

The Discovery Health study also found that, at least amongst South African communities, that the overall symptoms of Omicron might be milder, with adults “experiencing a 29% lower admission risk relative to South Africa’s first wave of infection… in early 2020,” according to Dr. Collie. “Furthermore, hospitalized adults currently have a lower propensity to be admitted to high-care and intensive-care units, relative to prior waves.”

This apparent mildness of symptoms comes with a major caveat, however, as there could be more than one reason for the study’s numbers: while it is possible that an Omicron infection might tend to result in mostly milder illnesses, South Africa’s population does not have a large proportion of elderly individuals that would be more susceptible to COVID-related complications, but instead is made up chiefly of younger people, many of whom have at least partial immunity after having already been infected with earlier iterations of the virus; amongst wealthier nations with larger elderly and immunocompromised populations, Omicron’s impacts could be much more severe in regards to hospitalization rates, meaning that hospitals could still be overrun by Omicron patients requiring urgent care.

“This could be a confounding factor for these hospital admission and severity indicators during this Omicron wave,” according to chief executive of Discovery Health Ryan Noach; until new data comes in from other parts of the world that might indicate otherwise, it would be best to assume that Omicron is as deadly as it’s Delta predecessor.

“Is Omicron milder, or more severe than Delta?” asks Dr. Michael Head, a Senior Research Fellow in Global Health with the University of Southampton, who was not involved with the Discovery Health study. “Time will tell.  The world’s finest scientists, including many in the global south such as in South Africa, will find out.  For now, national-level decision-makers have to consider that discretion is the better part of valour.”