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June 14, 2024

Lasting Immunity: The Latest on Omicron and COVID-19 Variants

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Jan 21, 2024

Recent studies suggest that Omicron infection results in robust, broad and lasting immune responses that can defend against emerging SARS-CoV-2 variants. This news comes as many parts of the world continue to lift COVID restrictions amid falling case counts.

Omicron Evasion of Innate Immunity Drives Stronger Adaptive Responses

According to a study published January 20th in Science Immunology, when Omicron infects lung cells its mutations allow it to partially avoid early innate immune defenses. This results in higher viral loads that drive stronger adaptive immunity:

“The mutations in Omicron allow it to evade mechanisms that usually detect viruses early during infection. And by avoiding or delaying these early immune mechanisms, Omicron replicates to much higher levels, which leads to increased adaptive immunity against SARS-CoV-2.”

While this evasion enables faster Omicron spread, it has an upside – infections produce very high levels of antibodies:

“So in essence, “Omicron exploits the human body in such a way that makes it mount a very high immune response to SARS-CoV-2. So essentially the person develops immunity that goes beyond just protecting that person against new infection from Omicron—it gives broad immunity to SARS-CoV-2 due to the high levels of neutralizing antibodies that are mounted.”

This data explains why Omicron infection confers such strong protection – even against variants that differ substantially from the original strain.

Hybrid Immunity From Infection and Vaccination

Another study published January 19th in Nature looked at healthcare workers in South Africa exposed heavily to COVID. It found 95% had hybrid immunity through some combination of infection and vaccination. Importantly, both vaccination after infection and breakthrough infections significantly increased immunity – especially T cell immunity. The breadth, longevity and strength of these responses suggest excellent capability to respond to emerging variants.

Hybrid immunity was extremely effective – only 1% of the healthcare workers lacked detectable immunity, and this group experienced high rates of reinfection during the study. In contrast, the group with hybrid immunity showed no reinfections. According to lead author Dr Alex Sigal:

“Our data suggest that natural infection and vaccination both contribute to immunity against SARS-CoV-2 reinfection, including against Omicron.”

This real-world data in high-risk individuals matches the growing consensus that hybrid immunity offers the strongest protection from severe COVID disease.

Lasting Immunity From All Variants Shows Key Evolutionary Trait

One analysis across 32 studies published January 18th suggests that Omicron evades immunity much like previous variants – by mutating spike proteins targeted by antibodies. Importantly, while this analysis showed Omicron is slightly better at evading immunity, it confirmed that immune responses still recognize the virus:

“The analysis suggests that the virus is not completely escaping pre-existing immunity induced by vaccination or previous infections, even with the highly mutated Omicron variants.”

According to the author, this indicates immune escape through spike protein mutation is likely to be a central strategy for SARS-CoV-2 evolution:

“Considering the extensive variation, SARS-CoV-2 variants seem to escape acquired immunity primarily by mutations of the viral spike protein without losing the ability to bind the ACE2 human receptor.”

In essence, the virus has strong evolutionary pressure to keep infecting cells – which requires ACE2 binding – but it avoids immunity by changing parts of the spike protein detected by our defenses.

What does this mean going forward? While COVID will likely continue to generate concerning new variants like Omicron, our immune systems recognize enough consistency across strains to mount protective responses. Viral evolution will enable ongoing transmission, but severe outcomes can be effectively prevented by updated boosters targeting newer circulating strains.

Current Situation and Outlook

Omicron drove record spikes in cases this winter, but its infectiousness combined with reinfections has rapidly increased adaptive immunity. Deaths and hospitalizations have been far lower than in previous waves, and early data suggests BA.2 may be even less severe while still providing robust protection from reinfection.

Falling Cases Enable Lifting Restrictions

With many parts of the world past peak infection, restrictions are now lifting in places like New York City and the UK:

NYC COVID Policy Shifts

Date Policy
Jan 17 NYC dropped indoor vaccine mandates
Feb 13 Mask mandates lifted for K-12 schools
Mar 1 Vaccine mandates for indoor dining, entertainment and gyms will be removed

Falling hospitalizations have created confidence measures like mask and vaccine mandates can be responsibly removed over the coming months. However, NYC also announced “Low Risk Days” – metrics-based guidelines for when restrictions may need to be re-implemented depending on conditions like case rates, hospitalizations and new variants. This data-driven approach balances increasing freedom with careful monitoring of risks going forward.

In the UK, Prime Minister Rishi Sunak indicated remaining COVID policies will be lifted by the spring, though the country could redeploy measures if dangerous new variants emerge:

“There’s hope ahead…but COVID isn’t over. There’s still uncertainty, still challenges, especially from new variants. So let’s move forward slowly and cautiously, taking each step together as one United Kingdom.”

With such high levels of hybrid immunity, the population now has the protections needed to largely remove restrictions. However governments emphasize flexibility to counter emerging outbreaks, signaling a targeted rather than blanketed policy approach going forward.

Updated Boosters Central to Ongoing Defense

A CDC report presented by vaccine expert Dr. Paul Offit argues that alongside natural immunity, updated Fall boosters will enable long-term control by protecting against severe disease:

“I think if we keep up to date with our vaccines, meaning this coming fall get the current vaccine for whatever variant is circulating, we have a way forward with this virus—that it becomes a mild seasonal virus.”

This aligns with the European strategy as EU health commissioner Stella Kyriakides noted Omicron-targeted boosters are already in the works:

“We need to consider all options for adapting vaccines to variants…and start exploratory work on variant-adapted vaccines so we are best prepared to determine if, when and which variant-adapted vaccines to develop for deployment by autumn 2023 if needed.”

An ongoing booster campaign using updated shots is therefore viewed as central to preventing viral mutations from fully overcoming current immunity – either from vaccines or infection.

Conclusion

While risks certainly remain from emerging variants, immunological evidence and falling hospitalizations signal the acute emergency phase of the pandemic is winding down in much of the world. However COVID-19 will remain an endemic virus humans must coexist with going forward. Periodic infections from new strains seem likely to become a regular occurrence for large portions of the population.

Fortunately, studies continue to demonstrate that vaccination, infection and hybrid immunity all provide lasting defenses against severe disease and death. Over time these exposures build immune memory capable of responding to severe breakthroughs infections from variants like Omicron, while updated boosters will fill gaps and enhance protection. Governments also now have proven tools like testing, treatments and behavioral measures that can be deployed against isolated outbreaks.

Many experts therefore believe while SARS-CoV-2 remains unpredictable, its evolutionary course combined with mounting hybrid immunity has put countries on track to steadily normalize policies and reopen societies in the months ahead. Dr Offit summarized the cautiously optimistic outlook:

“We can finally start to look ahead with hope, have a path forward.”

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AiBot scans breaking news and distills multiple news articles into a concise, easy-to-understand summary which reads just like a news story, saving users time while keeping them well-informed.

To err is human, but AI does it too. Whilst factual data is used in the production of these articles, the content is written entirely by AI. Double check any facts you intend to rely on with another source.

By AiBot

AiBot scans breaking news and distills multiple news articles into a concise, easy-to-understand summary which reads just like a news story, saving users time while keeping them well-informed.

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