What does herd immunity mean?

Herd immunity, or community immunity, is when a large part of the population of an area is immune to a specific disease. If enough people are resistant to the cause of a disease, such as a virus or bacteria, it has nowhere to go. While not every single individual may be immune, the group as a whole has protection.

What does COVID-19 efficacy mean?

Efficacy can refer to different things. For example, it can refer to how likely a person is to get COVID-19. A 0% efficacy would mean that vaccinated people in the research study were as likely to get COVID-19 as unvaccinated people.

When should you take a COVID-19 test if you were exposed to someone with COVID-19?

If you were exposed to someone with COVID-19, test yourself at least 5 days after your exposure. If you test negative for COVID-19, consider testing again 1 to 2 days after your first test. If you are going to an indoor event or a gathering, test yourself immediately before or as close to the time of the event as possible. This is especially important before gathering with individuals at risk of severe disease, older adults, those who are immunocompromised, or people who are not up to date on their COVID

How many types of COVID-19 vaccines are there?

There are three COVID-19 vaccines approved for use in the U.S. The Pfizer, Moderna, and Johnson & Johnson vaccines are all highly effective in protecting you from the virus that causes COVID-19. The CDC says there’s a preference for the mRNA (Pfizer and Moderna) COVID-19 vaccines over the Johnson & Johnson.

Can we reach herd immunity against COVID-19 through natural infections?

See full answerAttempts to reach ‘herd immunity’ through exposing people to a virus are scientifically problematic and unethical. Letting COVID-19 spread through populations, of any age or health status will lead to unnecessary infections, suffering and death.The vast majority of people in most countries remain susceptible to this virus. Seroprevalence surveys suggest that in most countries, less than 10% of the population have been infected with COVID-19.We are still learning about immunity to COVID-19. Most people who are infected with COVID-19 develop an immune response within the first few weeks, but we don’t know how strong or lasting that immune response is, or how it differs for different people. There have also been reports of people infected with COVID-19 for a second time.

When does herd immunity occur?

Herd immunity (or community immunity) occurs when a high percentage of the community is immune to a disease (through vaccination and/or prior illness), making the spread of this disease from person to person unlikely.