Pandemic or endemic? For now it's academic, say Covid-19 experts

Social media is buzzing with the theory that the Omicron variant of Covid is a positive development if it spreads like wildfire but does not cause severe disease, similar to flu and the common cold.

The disease would then be endemic, meaning it isn’t eradicated but circulates at a manageable level.

But experts say it is too early to make this call because we do not yet have enough data and other variants could be in the pipeline.

He said some people are speculating that Omicron “might be a step in this direction”, but added: “I regard it as too early to tell. Wait until it has reached the high-risk groups and see what it does to unvaccinated individuals who may still see much more severe disease. I am not holding my breath.”

Shabir Madhi, a professor of vaccinology at Wits University, said it is premature to conclude Omicron will be less virulent than earlier variants and that it will lead to Covid becoming endemic, “even if SARS-CoV-2 is likely to become endemic at some stage”.

He said it is “difficult to predict if it will outcompete Delta, and whether there won’t be further variants which are more transmissible that could outcompete Omicron in months to come”.

He added, however, that “early indications in Gauteng are that the rate of increase in Covid-19 hospitalisations and deaths, which usually lags behind by approximately two weeks relative to a surge in infections in the community, is lower than would have been expected for the rate of infections relative to the previous three waves”.

Preiser said shifting gears into the endemic phase in SA will require higher vaccination rates. “Looking globally, it seems that vaccine mandates are the only way to move above the ceiling of two-thirds vaccine coverage,” he said.

“It will require pressure of some sort to move to coverage which will allow our transition into the endemic phase with no risk of health-care service overload.”

Humans are the virus’s “food”, and when a disease is endemic it means we have “changed in the sense that we all acquire some degree of immunity” either through vaccination or natural infection.

Early data has shown cases rising exponentially without a surge in severe disease, and Madhi said: “If it transpires that the hospitalisation and death rates are low compared to what we experienced in the past despite a greater infection rate in the population, then we might be heading into the phase of SARS-CoV-2 being treated more as an endemic virus.”

Even if Omicron doesn't turn out to be the milestone signalling endemicity, the longer view for many global experts is that this status will eventually be reached.

This marks a major shift from earlier beliefs that societies would achieve herd immunity and that the disease could be eradicated. These two terms are no longer part of the global conversation, and earlier this year, in a paper published in science journal Nature, experts spelled this out. 

“Eradicating this virus right now from the world is a lot like trying to plan the construction of a stepping stone pathway to the moon. It’s unrealistic,” said Michael Osterholm, an epidemiologist at the University of Minnesota in Minneapolis.

“The future will depend heavily on the type of immunity people acquire through infection or vaccination and how the virus evolves.

“Influenza and the four human coronaviruses that cause common colds are also endemic, but a combination of annual vaccines and acquired immunity means societies tolerate the seasonal deaths and illnesses they bring without requiring lockdowns, masks and social distancing.”

According to scientists at the School of Public Health at Harvard University, there are too many variables to put a timeline on reaching endemicity.

“Since viruses spread where there are enough susceptible individuals and enough contact among them to sustain spread, it’s hard to anticipate what the timeline will be for the expected shift of Covid-19 to endemicity,” said Yonatan Grad and colleagues.

“It’s dependent on factors like the strength and duration of immune protection from vaccination and natural infection, our patterns of contact with one another that allow spread, and the transmissibility of the virus.”

They said the patterns will “likely differ considerably from what we saw with the other pandemics because of the heterogeneous responses to Covid across the world with some places engaging in ‘zero-Covid’ policies, others with limited responses, and widely variable vaccine availability and uptake.”