In early 1918, as World War I entered its final year, the H1N1 influenza A virus infected millions of people, causing the Spanish flu pandemic. In April 1920, after four waves and nearly 100 million deaths, the pandemic ended. H1N1 became much less lethal and caused only common seasonal flu. It had become an endemic virus.
Will history repeat itself? After two years of the COVID-19 pandemic and four waves of variants, will SARS-CoV-2 become an endemic virus?
After my latest opinion piece “Omicron May Help End the Pandemic This Winter” was published, readers asked if I could quote peer-reviewed publications to support my pandemic-ending claim. Well, since the Omicron wave is still going on, my projection can only be as good as a trained prediction. But things are looking pretty good.
In the past week, a couple of related research works have been published that point in the same direction – that Omicron spreads quickly, but is less pathogenic. None of them have yet been peer reviewed, and that is because these data are time sensitive, and so scientists choose to give the public access to their research “live” as the peer review process takes time.
So what do the new data suggest? Can the spread of Omicron end the pandemic? Well, waves come and go. For Omicron to be the last wave, it must be able to stimulate strong and long-lasting immunity to potential future variants.
T cell immunity and vaccination
The hope for long-term immunity depends on protective T cell responses. In my previous article, I cited a study from the University of Cape Town that shows that prolonged T cell response, induced by either vaccination or natural infection, cross-recognizes Omicron. The authors concluded that well-preserved T cell immunity to Omicron is likely to contribute to protection against severe COVID-19 caused by other variants.
It turns out that not all T cell responses are the same. The Cape Town study did not distinguish the types of T cell responses that a natural infection induces versus vaccination. We now know that although vaccinations with S-protein-based vaccines stimulate T cell responses, the responses do not induce protection. That’s why, even though the world had a high vaccination rate in November, the Omicron wave was still coming.
On January 10, the scientific journal Nature published a peer-reviewed article entitled “Cross-reactive memory T cells associate with protection against SARS-CoV-2 infection in COVID-19 contacts.” Posted to Nature by Imperial College London researchers five months ago, the article looked at T cell epitopes (very small protein fragments) from different SARS-CoV-2 proteins (S, N, E and ORF1) in terms of their cross-reactivity to them of other species of human coronavirus OC-43 and HKU1, which cause common cold.
They found a pool of T cell epitopes from S, N and ORF1 proteins that were cross-reactive between SARS-CoV-2 and human coronavirus (huCoV). However, the specific T cell response that induces protection is from the epitopes of the N and ORF1 proteins, not the S protein (peak protein). They then concluded that in the second generation of vaccines developed against COVID-19, non-spike proteins should be included.
When I read the paper, I was less interested in the researchers’ recommendation for next-generation vaccine development than I was in their study of proteins without spikes (N and ORF1) and the cross-reactivity of their T cell epitopes between SARS-CoV-2 and huCoVs, as this new information may shed light on detailed T cell immunity cross-protection between SARS-CoV-2 and huCoVs.
In other words, if the N-protein epitopes from colds could induce long-term protective T cell immunity to SARS-CoV-2, then Omicron infection with lots of N-protein epitopes should also be able to induce similar T-cell immunity and provide stronger protection against any future SARS-CoV-2 variant infections.
If you can recognize a distant cousin in a crowd, you can definitely spot your brother right next to you.
Light at the end of the tunnel
For about a year now, researchers have been discussing the potential of SARS-CoV-2 to join the other four human coronaviruses as an endemic virus.
SARS-CoV-2 is the seventh coronavirus to infect humans. We have MERS-CoV, which causes Middle Eastern respiratory syndrome, SARS-CoV and SARS-CoV-2, which cause severe acute respiratory syndrome, and the remaining four (OC43, HKU1, 229E and NL63) endemic viruses, which cause colds.
In a peer-reviewed paper entitled “Immunological Characteristics Control the Transition of COVID-19 to Endemic” published in the prestigious journal Science in February 2021, researchers at Pennsylvania State University and Emory University stated that all human coronaviruses elicit immunity with similar characteristics. The COVID-19 pandemic is a consequence of a human population that had not seen SARS-CoV-2 before. Once a widespread infection (such as the Omicron wave) occurs worldwide, the virus will eventually circulate endemically, meaning that infections can still occur, but with milder symptoms and much less mortality.
There are two reasons why the transition from pandemic to endemic did not occur before Omicron: 1) all the widespread vaccines are based on the nail protein, which does not induce protective long-term T cell response, and 2) natural immunity was not widespread.
The Nature paper revealed that protective (IL-2-secreting) T cells are induced by SARS-CoV-2 infection. Accordingly, we could predict that a wider spread of Omicron infection would induce a wider range of cross-reactive T cell immunity and subsequently offer more widespread protection against potential future SARS-CoV-2 variants. As a result, we are probably very close to being able to say goodbye to the pandemic.
Although we need to be aware that we are not out of the woods yet and people are still suffering, I remain optimistic that we are starting to see the light at the end of the tunnel.
We must also remember that even when we say goodbye to COVID-19, we will probably not be completely free of SARS-CoV-2. Even the seasonal flu kills more than half a million people globally each year, according to the World Health Organization. And another endemic virus is likely to increase the burden on healthcare systems around the world.
The good thing is, as I noted in my previous article, that Omicron can be seen as a live attenuated vaccine, which has a very good track record among all vaccines. There have been about 11 diseases that attenuated vaccines were widely used to fight, such as measles, mumps, chickenpox and polio. So far, none of these diseases have spread out of control after decades of vaccination.
Hopefully, Omicron will behave like its other weakened vaccine cousins, and with luck, no other SARS-CoV-2 variant will emerge and become a pandemic in the future.
The views expressed in this article are those of the author and do not necessarily reflect the views of the Epoch Times.