A health worker takes a nasal swab sample to test for COVID-19 at a facility in the Malad area of Mumbai, India, on April 30, 2021.

COVID-19 Variants: What You Need to Know

Here are the answers to your Frequently Asked Questions about SARS-CoV-2 Variants.

What is a virus variant? 

All viruses, including SARS-CoV-2, change over time, so new variants are expected to occur. Sometimes new variants emerge and disappear. Other times, new variants persist. For as long as the coronavirus continues to spread, new variants will continue to appear. 

Most changes have little to no effect on a virus's properties. But some changes can affect how easily a virus spreads; the severity of the associated disease; and/or the performance of vaccines, therapeutic medicines, diagnostic tools and other public health and social prevention and control measures.

Why are some variants more dangerous than the original coronavirus?

Some coronavirus mutations may enable the virus to spread faster from person to person, and more infections can result in more people getting very sick or dying.

What is the difference between variants?

UNICEF continues to monitor multiple variants as they are detected. There are four notable variants that have been detected in the United States so far:

  • Alpha (B.1.1.7): first detected in the U.S. in December 2020; initially detected in the United Kingdom
  • Beta (B.1.351): first detected in the U.S. at the end of January 2021; initially detected in South Africa in December 2020
  • Gamma (P.1): first detected in the U.S. in January 2021; initially identified in early January 2021 in travelers from Brazil who were tested during a routine screening at an airport in Japan
  • Delta (B.1.617.2): This variant, a sub-lineage of B.1.617, was first detected in the U.S. in March 2021; initially identified in India in December 2020

Why is the Delta variant especially dangerous?

The World Health Organization has categorized the Delta variant as a variant of concern (VOC) due to its high transmissibility compared to others; symptoms tend to be more severe than those associated with the original strain. Several countries have already seen outbreaks of the Delta variant. Research studies suggest that vaccines available to treat COVID are eight times less effective against this variant.

How prevalent is the Delta variant in the U.S.?

As of July 4, 2021, the Delta variant had spread to 111 countries, and accounted for 58 percent of infections in the U.S.

How are children affected by SARS-CoV-2 variants? 

SARS-CoV-2 transmission in a community correlates with the amount of infections in schools. When community rates of COVID-19 are high, there is an increased likelihood that SARS-CoV-2 will be introduced to, and potentially transmitted within, a school or child care setting.

Are current vaccines effective against variants?

So far, studies suggest that the current authorized vaccines work on the circulating variants; that COVID-19 vaccines offer a safe and reliable path to immunity against both the older strains of coronavirus and emerging strains, including the Delta variant.

According to a recent study published in the journal Nature, a double vaccination from BioNTech-Pfizer continues to provide strong protection from the Delta variant. Other studies conducted in countries where there is a predominance of Delta variant are showing that people who have been vaccinated are much less likely to get very sick or end up in the hospital.

Does mixing vaccine doses offer better protection against variants?


Will the vaccinated need booster doses to protect against newly discovered variants?

Studies on this are ongoing. Based on current information, the CDC advises those who have been fully vaccinated that they do not need a booster shot at this time.

What will happen if coronavirus variants continue to spread?

Viruses constantly change and become more diverse. Scientists are continuously monitoring these changes, including changes to the spikes on the surface of the virus. By carefully studying viruses, scientists can learn how changes to the virus might affect how it spreads and how sick people will get from it.

The variants that have been detected so far seem to spread more easily and quickly than other virus variants, which may lead to an increase in coronavirus cases — straining health care resources, leading to more hospitalizations and potentially more deaths.

Does UNICEF recommend that people continue to wear masks and practice physical distancing to prevent coronavirus spread — even as some countries are easing up on these guidelines?

UNICEF urges people to follow WHO, CDC and national guidance.

Learn more about UNICEF's work with partners to end the pandemic.

Top photo: A health worker takes a nasal swab sample to test for COVID-19 at a facility in the Malad area of Mumbai, India, on April 30, 2021. © UNICEF/UN0457046/Bandiwadekar