New SARS-CoV-2 Variants Still Spread Through the Air but Each Has a Unique Strategy to Stay Contagious
Nikhil Prasad Fact checked by:Thailand Medical News Team May 02, 2025 10 hours, 47 minutes ago
Medical News: Scientists from Imperial College London, The Pirbright Institute, and the MRC-University of Glasgow Centre for Virus Research have uncovered how different SARS-CoV-2 variants have managed to keep spreading through the air despite evolving mutations. Their study used a hamster model to analyze the airborne transmission abilities of both pre-Omicron and Omicron subvariants—shedding light on why some variants infect more easily than others, and how they are adapting to evade immunity while remaining contagious.
New SARS-CoV-2 Variants Still Spread Through the Air but Each Has a Unique Strategy to Stay Contagious
Even though strict public health measures and vaccines helped initially control COVID-19, the virus has continued to spread globally. One of the main reasons is its ability to evolve. The spike protein—used by the virus to enter human cells—frequently mutates, helping it escape immune defenses. However, this
Medical News report also emphasizes that mutations in other parts of the virus play a crucial role in enhancing airborne transmission, especially in new Omicron subvariants.
Airborne Transmission Remains a Key Threat
Using golden Syrian hamsters—an established model for studying COVID-19 transmission—researchers compared how the first-wave virus and newer variants like Alpha, Delta, and multiple Omicron subvariants (including BA.1, EG.5.1, BA.2.86, and JN.1) spread through the air. They employed a unique custom-built apparatus called the Infectious Virus Transmission Tunnel (IVT), which captures airborne particles exhaled by infected hamsters and measures the distance those particles can travel.
They found that even though Alpha variant hamsters emitted fewer virus particles into the air than the original strain or Delta, Alpha still spread efficiently. This was because Alpha had a lower "infectious dose" (ID50)—meaning it took fewer viral particles to cause infection. On the other hand, Delta produced more virus but needed a higher infectious dose to establish infection. This balance of emission versus infectiousness was a recurring theme in the study.
Omicron Subvariants Are a Mixed Bag
Omicron and its many offshoots presented more varied results. While some like EG.5.1 spread effectively, others like JN.1 and BA.2.86 showed very limited or no airborne transmission in the hamster model. The scientists determined that the ability of each variant to emit infectious airborne virus correlated closely with how well it spread. For example, JN.1 could barely be detected in airborne emissions and did not infect any of the exposed hamsters through the air.
Interestingly, when researchers created lab-modified versions of Omicron viruses—combining Omicron spike proteins with the backbone of the original Wuhan virus—they found airborne transmission improved dramatically. This suggests that non-spike genes in Omicron subvariants may be limiting the virus's ability to spread, at least in this animal model.
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Why This Matters
The study offers a clearer understanding of how different variants retain their airborne contagiousness even as they mutate to dodge immune responses. Measuring the ID50 and airborne viral emissions can help predict how infectious new variants might be. This could become a vital tool in deciding public health responses and designing new vaccines or therapies.
The researchers also emphasized that viral RNA alone (commonly used in PCR tests) does not always reflect how contagious someone is. They observed that infectious virus levels drop quickly after the first couple of days of infection—even when PCR tests remain positive. That means a person might test positive but not necessarily be able to infect others, reinforcing the idea that isolation periods should consider how long airborne virus is actually exhaled.
A Balanced Evolution
In conclusion, the research shows that SARS-CoV-2 variants maintain airborne spread using different strategies. Some emit more virus, others need fewer particles to infect. This evolution allows the virus to balance immune evasion and transmission. Tools like the IVT can help identify which emerging variants are more likely to spread rapidly. The findings also suggest that genetic elements outside the spike protein are crucial in determining how infectious a variant truly is. Understanding these mechanisms could be key to stopping the next wave before it starts.
The study findings were published in the peer reviewed journal: npj Viruses.
https://www.nature.com/articles/s44298-025-00120-1
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