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In the U.S., COVID-19 hospitalizations and deaths are overall significantly lower, but there are hot spots of surging infections attributable to the Delta variant. Here, an infectious-disease doctor breaks down everything you need to know about the new strain and how to continue to stay safe.
What is the Delta variant?
The SARS-CoV-2 virus can mutate into different variants over time. The Delta variant (B.1.617.2) was first identified in India in December 2020. The CDC has classified variants with a grading system, and Delta is a variant of concern because it is much more transmissible. The Delta variant is 40 to 60% more transmissible than the Alpha variant identified in the U.K. (which was 50% more transmissible than the first virus identified in Wuhan, China). The Delta variant has spread rapidly, becoming the dominant strain in the U.K., despite the high vaccination rate, and is on track to become the lead strain in the U.S., where less than half the population is fully vaccinated. This variant is also concerning because it causes more severe disease, doubling the risk of hospitalization.
How will the Delta variant impact the course of the pandemic?
In March, the more contagious Alpha variant rapidly spread in the U.S., but its effect was blunted by rising vaccinations. The Delta variant, however, seems to be finding a foothold in communities that are partially or minimally vaccinated.
One of the leading Delta variant hot spots is my own region in St. Louis. We are seeing a sharp increase in COVID-19 infections and hospitalizations, especially in the southwestern part of the state. Virtually all hospitalizations appear to be of unvaccinated or partially vaccinated individuals. Midwestern and southern regions with low vaccination rates and hot summers that drive people indoors may experience multiple local surges.
Beyond the U.S., the Delta virus poses a potentially catastrophic risk to regions without adequate access to vaccination or prior exposure.
Will vaccination protect me from the Delta variant?
Yes. Receiving both doses of mRNA vaccinations (Pfizer-BioNTech, Moderna) and AstraZeneca vaccines provides high levels of protection, with >92% protection from hospitalization. A small percentage may still get symptomatic illness, but they are less sick. Recently a large study of the Johnson & Johnson vaccine also showed robust protection against multiple variants, including Delta.
The Delta variant, however, is more transmissible to those who are partially vaccinated: Receiving only one dose provided much less protection against the Delta relative to other variants (only 33% against symptomatic disease). Unvaccinated people continue to be at the highest risk, experiencing high rates of infection and its complications, including hospitalization, death, and long-haul symptoms. Vaccination remains one of the major strategies to protect everyone from infection with all variants.
Why aren’t people getting vaccinated?
There are still barriers to access for those who are eligible for the vaccine. Although more than three billion vaccine doses have been administered, there are stark global disparities in access. Vaccine hesitancy continues to be a major hurdle. Ideology is a major predictor of not being vaccinated, as is age. (Younger adults age 18 to 29 have the lowest vaccination rate.) Children under 12 will not be eligible for the vaccine for a while—as late as next year. Wherever vaccination levels are low, the virus has the opportunity to continue to develop more variants. Aggressive mass-accessible vaccination is still the major key to preventing further harm from COVID-19 infections.
What about masking?
In May, the CDC changed the U.S. masking recommendations, noting fully vaccinated people no longer needed to mask even indoors. Last week, however, the WHO again emphasized their ongoing recommendation that all individuals, including those who are vaccinated, should wear masks indoors. Since the ascendance of the Delta variant, numerous regional health departments in the U.S. have also revisited masks for indoor use for all people regardless of vaccination status. That includes the country’s most populous county, Los Angeles County, and hot spots including the St. Louis region.
The contrary advice can be confusing, but it is consistent in this way: Public-health measures adapt to the changing state of the pandemic and local circumstances. In the U.S., general case levels have been low, while globally they are not. The Delta variant changes the calculation, so masking rules are being reevaluated. The challenge, however, is that getting pandemic-weary populations to reinstate lockdowns and mask rules can be difficult in practice.
What should I do to stay safe?
First, if you have not yet been vaccinated, then get vaccinated. Know that you will not be fully protected until at least a week or two after the second dose. Vaccination remains the single most safe and effective strategy for protecting yourself and those around you.
If you are unable to get vaccinated, or if you are only partially protected from vaccination due to immunodeficiencies, continue to practice social distancing and masking. Follow the two-out-three rule of thumb—when near members of other households, ensure two of the following conditions: ventilation, distancing, or masking.
Second, follow your local conditions. If cases are surging in your region, pay attention to the recommendations of local authorities. If there are concerning case rises, especially in regions where vaccination is low, continue masking indoors even if you are vaccinated. The reason for this is that if the Delta variant is surging in your area, the vaccine will protect you from serious illness, but you may still be passing it on to others. There is good evidence that the vaccines reduce transmission, but the Delta variant may decrease that protection. Even if you’re vaccinated, mask indoors—especially if you have unvaccinated household members (like children) or visit places like grocery stores, where people with lower immunity still frequent.
We have come a long way during this global health crisis, and people are understandably looking for relief and connection after such a long, difficult slog. Vaccination has been a stunning triumph and continues to deliver protection. The pandemic, however, is in full force throughout the globe as we try to scale up vaccination access and uptake before the mutating virus takes a larger toll.
Dharushana Muthulingam, M.D., M.S., is an infectious-disease physician and public-health researcher in St. Louis.