Evidence is mounting that the Northern Hemisphere could see an increase in COVID-19-related COVID-19 cases this fall/winter. Scientists suspect that many COVID-19 cases could be caused by new immune-evading and behavior changes as well as declining immunity.

Nature discusses the factors that could lead to a surge and what countries can do to reduce the impact of new Omicron vaccines.

Is There A Covid-19 Wave This Winter And Autumn?

A collaborative effort, the COVID-19 Scenario Modeling Hub, presented several scenarios for the United States during mid-August. After the spikes in cases due to the BA.5 Omicron variant, the models showed that the United States could have a relatively quiet COVID-19 season as long as vaccination booster campaigns were initiated quickly and new variants weren’t developed. Even with the new variant, a significant increase in cases was unlikely.

Justin Lessler from UNC Chapel Hill is the lead of the modeling effort. He said that hospitalizations have fallen in line with projections for more than a month. Other factors could also be a problem. Lessler states that boosters have been slow to roll out, which are designed to target Omicron as well as the original SARS virus CoV-2 strain.

There are subtle signs Omicron could be evolving and creating new immunity-dodging varieties. Lessler said, “It could cause some rises in the autumn and winter months.” Jennifer Nuzzo, an epidemiologist at Brown University (Rhode Island), says that some states are already experiencing an increase in cases.

The weekly SARS-CoV-2 Infection Survey, which is the gold standard for COVID-19 data in the United Kingdom, revealed an increase in COVID-19 cases in England and Wales compared to its previous reports. It is still very low but the number of people with SARS-CoV-2 is growing rapidly in Britain.

Research suggests that there are a number of immune-dodging options being developed worldwide. These options will drive an autumn-winter surge.

Increased Case Numbers

It is highly unlikely, according to Tom Wenseleers, an evolutionary biologist at the Catholic University of Leuven in Belgium. SARS-CoV-2 is increasing due to a decrease in immunity from previous infections and vaccines. This pandemic is also affecting more people than ever before. According to health officials, social dynamics in many countries have nearly returned to pre-pandemic levels. This includes the United Kingdom. Others respiratory viruses can flourish in cooler months. This could be due to more indoor time.

Is there a new Omicron strain in the pipeline for this fall?

These mutations may include three or more. It is possible to see at least three of these Omicron sub-variants driving past waves — BA.2, Ba.4 or Ba.5 — but their descendants are gaining mutations that could help them spread.

According to Tom Peacock, a virologist at Imperial College London, SARS-CoV-2-watchers monitor an unprecedented number of variants from many branches within the Omicron family. Although these variants are from different ancestries, they share many of the same mutations within the SARS-CoV-2 spike protein (the part of the virus that the immune system targets). Peacock states, “Clearly there’s an optimal way for a variant to look going into the Season.”

Researchers pay attention to sublineages. BQ.1’s rapid rise in Europe and the United Kingdom could be attributed to several key changes made by BA.5 (a descendant from BA.5). Rajesh Karyakarte, based in Pune, coordinates SARS/CoV-2 gene sequencing in Maharashtra. He says that India’s spawn from the BA.2.75 variant which caused an infected wave a few months ago is outperforming all other spawns.

His team sequenced samples in September, and discovered that the most common subvariant was named BA.2.75.2. It was closely followed by a relative. BA.2.3.20, another variant of BA.2, is also rapidly growing in Singapore. It has also been discovered in Australia & Denmark.

Wenseleers states that “at least one variant or combination will cause an epidemic wave.” This is because they all act in the same way so “it doesn’t really matter which one becomes the next big thing.”

Why is this Variant on the Rise?

Two words: immune escape. Researchers are currently studying multiple variants of spike proteins. All of these variants have multiple overlapping changes in the receptor binding domain. These are the areas where powerful infected-blocking antibody targets. Yunlong Richard Cao is an immunologist at Beijing’s Peking University. He believes multiple viruses are producing the same spike mutations. This is a significant advantage in spreading the virus.

Cao and his colleagues evaluated the potential of the new crop varieties to evade neutralizing antibodies from vaccination and previously infect with other variants. BQ.1.1, which is a member of the BQ.1 familia, had an additional spike change and was found to be the most immune-evasive.

They were able to evade most of the neutralizing antibodies that can be elicited by infection with BA.5. Two anti-omicron drugs were still effective against BA.2 and BA.5, but they are less effective against emerging Omicron subvariants. Peacock was part of another team that reached similar conclusions about BA.2.75.2. Cao believes that there is an incredible degree of immune escape right now.

How Big are the Autumn-Winter Waves?

Wenseleers estimates that autumn-winter waves will be similar in size to the ones seen in BA.5 surges based on preliminary estimates. This includes the impact on infection rates. It is hard to predict how hospitalizations will change. Researchers believe that admissions will be lower due to the increase in immunity from vaccinations and previous infections than they were during previous COVID-19 waves.

It is unknown how low this effect might be. Lessler states that although it’s a different game in 2020 and 2021, a surge would still be associated with an increase in deaths and hospitalizations.

Even a mild COVID-19 epidemic could pose problems for hospitals. Already, they are facing backlogs and other conditions which place a substantial burden on the winter health system. Influenza, which hasn’t been detected in the Northern Hemisphere over the past two winters, is expected to return this season. This could lead to fears of a double epidemic of influenza and COVID-19. Lessler states that hospitals can be quite stressed during a bad flu season.

What do you think about the new vaccines?

Boosters such as bivalent vaccines can provide some protection against infection by new variants. Scientists warn this protection might not last long. Scientists believe one component of bivalent vaccines is built upon an Omicron subvariant — BA.1 in the UK and BA.5 in the United States.

Some evidence suggests that vaccines increase the production of Omicron-specific neutralizing antibodies. These antibodies help identify the original virus from which the vaccines were developed. Cao suggests boosters might be necessary to produce high levels of Omicron-specific neutralizing antibodies.

All evidence suggests that COVID-19 vaccines are highly effective in the prevention of severe diseases. Nuzzo believes that this should be the main goal of all winter and autumn booster programs. This means booster programs should target those most at-risk for severe diseases, such as seniors and people with underlying conditions. She said, “We need to focus a laser beam of protection against severe illness.”