by Health Desk | Published on July 6, 2022 – Updated on July 6, 2022 | Explainer

What our experts say

Early data suggested that the Omicron variant appeared to cause less severe infection symptoms and lower rates of hospitalization. Data still suggests that Omicron subvariants cause less severe infection than previous variants like Delta, but it’s not clear by how much, and it’s not clear if this is true for all existing or potential future subvariants. What data is clear on is that subvariants of Omicron can cause both short and long-term symptoms and challenges, including hospitalization and death. In addition, Omicron is more contagious than previous variants.

Omicron subvariants BA.5 and BA.4 are currently spreading around the world. It can be challenging to track the spread of the virus because so many people have some level of immune protection either from infection or vaccination. This makes it harder to understand the isolated effects of one specific variant or subvariant. Further, the increase in use of at-home antigen tests has led to under-reporting of COVID-19 cases because fewer people are taking PCR tests which are often tracked by local and national health authorities.

What we do know, however, is that Omicron BA.5 appears to be able to evade some immune systems that have already been infected by or vaccinated against the virus. People who have been fully vaccinated and infected may even be reinfected several times, and increase their risk of poor health outcomes with each infection.

The ability of vaccines to prevent severe infections, hospitalizations, and death in the face of Omicron is uncertain given how many mutations each Omicron subvariant has. Many factors influence how severe symptoms might be for someone including prior infection, age, vaccination history, health conditions, and others.

Omicron subvariants continue to spread at unprecedented rates and more research and data are needed to determine the full impact of Omicron.

Context and background

The term “mild” for a virus or variant is misleading because there are a number of factors that might make something mild or severe. For instance, though data suggests that Omicron causes less severe symptoms and health outcomes than other previous variants, there are a few characteristics that one could argue make this variant not mild. For instance: 1) its high transmissibility, 2) the fact that Omicron is a variant that many people are getting reinfected with (which increases risk of poor outcomes), and 3) the potential ability for some Omicron subvariants to evade immunity.

There are many factors that play into how severe a virus or variant is for the health of an individual or society, and they all need to be considered. Calling any variant of COVID-19 is misleading and an oversimplification.

Resources

1. Is Omicron really less severe than previous COVID-19 variants? (Gavi)
2. Omicron and BA.5: A Guide to What We Know (Yale Medicine)
3. Omicron Variant: What You Need to Know (United States Centers for Disease Control and Prevention)
4. Differential Pathogenesis of SARS-CoV-2 Variants of Concern in Human ACE2-Expressing Mice (Viruses)
5. What Omicron’s BA.4 and BA.5 variants mean for the pandemic (Nature)
6. SARS-CoV-2 variants of concern as of 30 June 2022 (European Centre for Disease Prevention and Control)
7. Neutralization Escape by SARS-CoV-2 Omicron Subvariants BA.2.12.1, BA.4, and BA.5 (The New England Journal of Medicine)
8. Intrinsic Severity of the SARS-CoV-2 Omicron Variant (The New England Journal of Medicine)\

Used with Permission from Health Desk, a public health hub that explains emerging COVID-19 science.