Delta Variant: What We Know About the Science
The Delta variant is more contagious: The Delta variant is highly contagious, nearly twice as contagious as previous variants.
Unvaccinated people remain the greatest concern: The greatest risk of transmission is among unvaccinated people who are much more likely to contract, and therefore transmit the virus.
Some data suggest the Delta variant might cause more severe illness than previous strains in unvaccinated persons. In two different studies from Canada and Scotland, patients infected with the Delta variant were more likely to be hospitalized than patients infected with Alpha or the original virus strains.
Safety of COVID-19 Vaccines
Like all vaccines, COVID-19 vaccines go through a rigorous, multi-stage testing process, including large clinical trials that involve tens of thousands of people. These trials are specifically designed to identify any safety concerns.
The vaccines have shown a high level of efficacy across all populations. Vaccines have been found to be safe and effective in people with various underlying medical conditions that are associated with increased risk of severe disease. These include high blood pressure; diabetes; asthma; pulmonary, liver or kidney disease; and chronic infections that are stable and controlled.
Vaccine Protection and Transmission
COVID-19 vaccines are crucial tools in the pandemic response and protect against severe disease and death. Vaccines provide at least some protection from infection and transmission, but not as much as the protection they provide against serious illness and death. More evidence is needed to determine exactly how well they stop infection and transmission.
After being vaccinated, individuals should continue taking simple precautions, such as physical distancing, wearing a mask, keeping rooms well ventilated, avoiding crowds, cleaning hands, and coughing into a bent elbow or tissue. Get tested if you are sick, even if you’ve been vaccinated.
COVID-19 Vaccination and Fertility
- COVID-19 vaccination is recommended for everyone 12 years of age and older, including people who are trying to get pregnant now or might become pregnant in the future, as well as their partners.
- Currently no evidence shows that any vaccines, including COVID-19 vaccines, cause fertility problems (problems trying to get pregnant) in women or men.
- If you get pregnant after receiving your first shot of a COVID-19 vaccine that requires two doses (i.e., Pfizer-BioNTech COVID-19 vaccine or Moderna COVID-19 vaccine), you should get your second shot to get as much protection as possible.