COVID-19 is back. Again.
With masks coming off and highly transmissible subvariants of omicron circulating, people who鈥檝e made it through the pandemic without getting SARS-CoV-2 are suddenly getting it.
People who鈥檝e had it already are getting it .
It鈥檚 Oregon鈥檚 seventh surge.
It鈥檚 unfolding in a radically changed world, where most of our immune systems have some antibodies, from vaccines or previous infection, to deploy against the virus.
That鈥檚 curbing the virus鈥� terrors, if not its spread.
At the peak of the delta wave last summer, there were 197 COVID-19 patients on life support in Oregon. Last week, fewer than 10.
OPB took its questions about the current wave and what it says about the long-term trajectory of the pandemic to Bill Messer, an expert in viral evolution and a clinician who cares for COVID-19 patients at OHSU.
Here are his observations about what COVID-19 is doing now, and where the pandemic is .
1. Things are getting better.
The number of reported cases is way up, close to the peak during the delta wave last summer.
But the number of deaths and hospitalizations remains comparatively low.
And that makes sense. There are more cases in people with some degree of protection from vaccines or previous infection, and the omicron variant is less virulent than delta.
鈥淚t may be that it becomes a seasonal respiratory virus but that it won鈥檛 carry with it the same horrific, devastating impact on our health care infrastructure going forward that it did early in the pandemic,鈥� Messer said.
鈥淲e鈥檙e seeing more and more evidence to suggest that that is indeed a likely pattern.鈥�
Messer cautions, however, that it鈥檚 too soon to say for sure if the health effects of COVID will continue to lessen, and there are multiple evolutionary paths the virus can take from here.
2. The omicron variants are super contagious.
We may be approaching the limit of how much more contagious the coronavirus can get.
One of the major ways variants gain an evolutionary advantage is if they have mutations that make them more transmissible.
Each dominant variant of the COVID-19 virus has been more transmissible than the one it replaced.
You can see that looking at how the virus鈥� reproduction number, R0, . The number measures how many new people each person with the virus infects, absent interventions like masking or vaccines.
The ancestral strain of SARS-CoV-2 had an R0 of between 2 and 3. That R0 increased to around 6 for the delta variant. The R0 is around 12 for the omicron subvariants circulating now.
That makes the novel coronavirus already contagious viruses ever, on par with chicken pox, but not quite as contagious as the measles.
Messer suspects SARS-CoV-2 is reaching the limit of how much more contagious it can get.
鈥淭he number of new cases that arise from a single case cannot continue to rise infinitely,鈥� he said. 鈥淚t鈥檚 going to plateau somewhere.鈥�
That hard limit is due to physical realities, like how many people we can come into contact with while infectious, or how much we can sneeze.
There鈥檚 always room for incremental increases, but Messer is not expecting another huge leap in contagiousness.
3. The current variants are better at reinfecting us.
One of the most intriguing aspects of the omicron subvariants is their capacity for immune evasion: the ability to reinfect people who鈥檝e been infected with other COVID-19 variants and to cause breakthrough infections in vaccinated people.
There are likely a couple of reasons for this. First, research has shown that our immunity to COVID-19 wanes relatively quickly.
And evolution favors variants with mutations that help the virus evade our immune response.
Messer believes that going forward, we will likely see new variants that are better at reinfecting us.
Interestingly, this ability to cause repeat infections relatively frequently is a trait SARS-CoV-2 appears to share with other important coronaviruses: the four viruses that cause the common cold.
Messer said recently learned that People are reinfected with cold viruses about once every 30 months, with evidence that some people can experience multiple infections from the same cold virus within six months or less.
Some of those repeat infections may be too mild to cause symptoms.
Messer believes it鈥檚 reasonable to think a similar pattern may emerge with COVID-19, where people get short-term immunity from infection or vaccination, but a vaccine that confers five-year immunity is off the table.
鈥淚t looks like it鈥檚 going to be shorter than that, and it is going to be seasonal and cyclical,鈥� he said.
4. How sick you鈥檒l get with each infection is a key unknown.
While vaccination and prior infection won鈥檛 completely protect you from COVID-19, you do retain some antibodies that can mount a response to future infections.
Even waning antibodies offer decent protection against the most severe outcomes, like hospitalization and death.
But long-term antibody protection may wane over time, and reinfections are still causing relatively serious symptoms for many people, Messer said.
In terms of its ability to disrupt our lives and cause pain, there鈥檚 still a huge difference between catching a seasonal COVID-19 variant once a year and a seasonal cold.
Messer said it鈥檚 hard to know why. It could be that SARS-CoV-2 is just a little different, and nastier, than the common cold coronaviruses.
Or, it could appear nastier because it鈥檚 still very early days in this pandemic, from an evolutionary point of view.
We don鈥檛 know how long the four viruses that cause the common cold have been circulating, or if they also appeared more virulent at first.
There is one intriguing set of clues, however.
Some scientists believe they have pinpointed how and when one of the four common cold viruses, human coronavirus OC43, was introduced.
If they鈥檙e right, it鈥檚 a scenario with many echoes of the current pandemic.
The researchers have hypothesized that OC43 leaped from cattle to humans about 130 years ago.
It may have been of a well-documented global respiratory pandemic that killed more than 1 million people from 1889 to 1891.
If that is correct, Messer said, it strengthens the argument that over some period of years and many repeat infections, SARS-CoV-2 will become a less terrible virus.
鈥淭he counterargument is the virus is really agnostic about how virulent it is, it really just wants to be transmissible and survive from host to host,鈥� he said.
5. Reformulating vaccines will be tricky
The vaccine most of us have received was formulated to protect against the first COVID-19 virus we encountered. While it鈥檚 still providing protection against the worst outcomes of infection, it鈥檚 not a great fit for the omicron subvariants.
Pfizer and Moderna are an omicron variant vaccine, but those efforts are moving .
Messer said designing antigens for an omicron variant vaccine isn鈥檛 that hard.
The bigger problem is whether a new vaccine will earn or lose money for its maker.
Vaccine makers need to see that the public is willing to get an updated version of the COVID-19 vaccine to make it worth investing in it, Messer said.
That may depend in part on how mild, or severe, breakthrough infections are for people who鈥檝e already been vaccinated.
In addition, vaccine makers will need to bet that the omicron variants will still be the dominant branch of the COVID-19 family tree when a vaccine is ready to get into arms. The virus鈥� rapid evolution makes that uncertain.
鈥淚 don鈥檛 see the clear path forward to the investment in rolling out the next variant vaccine paying off. That鈥檚 a cynical way of looking at it,鈥� Messer said.
6. One simple takeaway: Get your booster.
Messer has yet to catch COVID-19 himself. Part luck, part care, part the privilege of working in a place with masking and good hand hygiene.
He said people like him who are vaccinated but haven鈥檛 been infected are likely pretty susceptible to getting COVID-19.
The data is clear that antibodies you get from vaccination wane relatively quickly. And that is a reason, according to Messer, to follow his advice.
鈥淚f you haven鈥檛 gotten a booster,鈥� he said, 鈥渄o it now.鈥�
Copyright 2022
