COVID-19 is back. Again.
With masks being taken off and highly transmissible subvariants of Omicron floating around, people who made it through the pandemic without getting SARS-CoV-2 are suddenly getting it.
People who already had it will get it again.
It’s Oregon’s seventh climb.
It is unfolding in a radically changed world where most of our immune systems have some antibodies from vaccines or previous infections that can be turned against the virus.
This will contain the horrors of the virus, if not its spread.
At the peak of the delta wave last summer, 197 COVID-19 patients were on life support in Oregon. Last week it was less than 10.
OPB directed its questions about the current wave and what it says about the long-term course of the pandemic to Bill Messer, a viral evolution expert and clinician who cares for COVID-19 patients at OHSU.
Here are his observations on what COVID-19 is doing now and where the pandemic is headed.
1. Things are getting better.
The number of reported cases is way up, near the peak during last summer’s delta wave.
But the number of deaths and hospital admissions remains comparatively low.
And that makes sense. There are more cases in people with some degree of protection from vaccination or previous infection, and the Omicron variant is less virulent than Delta.
“It may be that it becomes a seasonal respiratory virus, but that it doesn’t bring with it the same terrible, devastating impact on our healthcare infrastructure that it did when the pandemic began,” Messer said.
“We’re seeing increasing evidence that this is indeed a likely pattern.”
However, Messer warns that it’s too early to say for sure whether the health effects of COVID will continue to subside, and that there are several evolutionary paths the virus can take from here.
2. The Omicron variants are super contagious.
We may be nearing the limit of how much more contagious the coronavirus can become.
One of the most important ways variants gain an evolutionary advantage is by having mutations that make them more transmissible.
Each dominant variant of the COVID-19 virus was more easily transmissible than the one it replaced.
You can see that by looking at how the R0 reproduction number of the virus has changed. The number measures how many new people each person infects with the virus without interventions like masking or vaccines.
The ancestral strain of SARS-CoV-2 had an R0 between 2 and 3. This R0 increased to around 6 for the Delta variant. The R0 is around 12 for the currently circulating Omicron subvariants.
This makes the new type of corona virus one of the most contagious viruses of all, comparable to chickenpox, but not quite as contagious as measles.
Messer suspects that SARS-CoV-2 is reaching the limit of how much more contagious it can become.
“The number of new cases arising from a single case cannot go on increasing indefinitely,” he said. “There will be a plateau somewhere.”
This hard limit is due to physical realities e.g. B. how many people we can come into contact with while we are contagious or how much we can sneeze.
There is always room for incremental increases, but Messer does not expect another large increase in the risk of contagion.
3. The current variants are better at reinfecting us.
One of the most intriguing aspects of the Omicron subvariants is their immune evasion ability: the ability to reinfect people infected with other COVID-19 variants and cause breakthrough infections in vaccinated people.
There are probably several reasons for this. First, research has shown that our immunity to COVID-19 wears off relatively quickly.
And evolution favors variants with mutations that help the virus evade our immune response.
Messer believes that in the future we will likely see new variants that are better able to reinfect us.
Interestingly, this ability to cause repeated infections relatively frequently is a trait SARS-CoV-2 appears to share with other major coronaviruses: the four viruses that cause the common cold.
Messer said researchers recently learned that people get reinfected with cold viruses about every 30 months, with evidence that some people can contract multiple infections from the same cold virus within six months or less.
Some of these repeated infections can be too mild to cause symptoms.
Messer thinks it’s reasonable to assume that a similar pattern could emerge with COVID-19, where people get short-term immunity to an infection or vaccine, but a vaccine that confers five-year immunity is off the table.
“It looks like it’s going to be shorter, and it’s going to be seasonal and cyclical,” he said.
4. How sick you get with each infection is an unknown key.
While vaccination and previous infection do not fully protect you from COVID-19, they do retain some antibodies that can trigger a response to future infections.
Even dwindling antibodies offer adequate protection against the most serious consequences, such as hospitalization and death.
However, long-term antibody protection can wear off over time, and reinfections still cause relatively severe symptoms in many people, Messer said.
In terms of its ability to disrupt our lives and cause pain, there is still a big difference between contracting a seasonal COVID-19 variant once a year and catching a seasonal cold.
Messer said it’s hard to know why. It could be that SARS-CoV-2 is just a little different and more nasty than the common cold coronaviruses.
Or it might seem more awkward because it’s very early in this pandemic from an evolutionary perspective.
We do not know how long the four cold viruses have been around or whether they initially appeared more virulent.
However, there is an intriguing set of clues.
Some scientists believe they have pinpointed exactly how and when one of the four cold viruses, human coronavirus OC43, was introduced.
If they are right, it is a scenario with many echoes of the current pandemic.
The researchers hypothesized that OC43 jumped from cattle to humans about 130 years ago.
It may have been the cause of a well-documented global respiratory pandemic that killed more than 1 million people from 1889 to 1891.
If that hypothesis is correct, Messer said, it strengthens the argument that over a period of years and many repeated infections, SARS-CoV-2 will become a less terrifying virus.
“The counterargument is that the virus is really agnostic about how virulent it is, it really just wants to be transmissible and survive from host to host,” he said.
5. Vaccine reformulation will be difficult
The vaccine most of us received was formulated to protect against the first COVID-19 virus we encountered. Although it still offers protection against the worst effects of infection, it does not pair well with the omicron subvariants.
Pfizer and Moderna are developing an Omicron variant of the vaccine, but those efforts are slow.
Messer said developing antigens for an omicron variant of the vaccine is not that difficult.
The bigger problem is whether a new vaccine makes or loses money for its manufacturer.
Vaccine manufacturers need to see that the public is willing to receive an updated version of the COVID-19 vaccine to make it worth investing in, Messer said.
That may depend in part on how mild or severe breakthrough infections are for people who have already been vaccinated.
Additionally, vaccine makers must bet that when a vaccine is ready to hit the streets, the Omicron variants will still be the dominant branch of the COVID-19 family tree. The rapid evolution of the virus makes this uncertain.
“I don’t see the clear path to investing in rolling out the next vaccine variant paying off. That’s a cynical way of looking at things,” said Messer.
6. A simple realization: get your booster.
Messer has not yet contracted COVID-19 itself. Part luck, part diligence, part privilege to work in a place with masks and good hand hygiene.
He said people like him who are vaccinated but have not been infected are likely to be quite vulnerable to COVID-19.
The data clearly shows that the antibodies you get from vaccination wear off relatively quickly. And according to Messer, that’s one reason to follow his advice.
“If you haven’t gotten a refresher already,” he said, “do it now.”