The global emergence of the highly infectious Delta variant of the coronavirus has prompted public health officials around the world to re-evaluate COVID-19 mitigation policies.

Even if vaccination rates continue to rise—in the United States, approximately 46.8% of the population is fully vaccinated—people are increasingly concerned The outbreak will hit the pockets of the country Places where immunity is relatively low.

The Delta variant was first discovered in India, where the epidemic has been raging for several months, and has since been discovered in at least 85 countries/regions. In the United States, its prevalence has doubled in the past two weeks and now accounts for one-fifth of COVID-19 cases, compared to only 2.8% in the two weeks ending May 22.

Eric Topol, a professor of molecular medicine at the Scripps Research Institute, said in a statement: “It is the super-transmissible and most contagious version of the virus we have seen so far. If it is, it must be a super-spreading strain interview Scientific american Tuesday.

According to a study, there is also some evidence that Delta variants can cause more serious COVID-19 disease and hospitalization. Scottish research published in The LancetData on how deadly the Delta variant is compared to previous viral forms are still to be determined by future research.

Early research on the effectiveness of the COVID-19 vaccine against Delta variants suggests that those who are fully vaccinated may have a protective effect.

A kind Preprint study by the Department of Public Health, UK It was found that the effective rates of two doses of Pfizer vaccine and two doses of AstraZeneca vaccine were 96% and 92%, respectively. These numbers are similar to the effectiveness against other variants, and it seems that only one dose of these vaccines can provide some degree of protection.

Moderna announced on Tuesday that it has conducted preliminary tests on the sera of vaccinated people Show that the company’s vaccine is effective Also opposed to Delta variants.Infectious disease experts are weighing single doses Johnson & Johnson vaccine may need to be boosted To improve its effectiveness.

But as countries and cities in Asia and Australia Enter another round of blockade, People are increasingly worried about whether the vaccination rate can keep up with the spread of Delta variants.Even in the UK, where vaccination rates are relatively high, Delta variants have rapidly developed Soaring to become a dominant strainThis model is similar to the previous alpha variant in the UK, which preceded the sharp rise in the number of infections in the United States.

The World Health Organization urged last Friday Continue to wear masks even among vaccinated peopleSo far, CDC has not adopted this measure in the United States.In most parts of the United States, mask regulations and other COVID-19 restrictions have been phased out, including Pennsylvania Fully lifted its general mask regulations this week.

In Philadelphia, COVID-19 restrictions and mask requirements Lifted earlier this month, The health department did not indicate that the city intends to restore the requirements for masks due to the Delta variant.

Acting Philadelphia Health Commissioner Dr. Cheryl Bettigole Published an open letter last week Warn about the risks of Delta variants and the urgent need to increase vaccination rates-sooner rather than later. Those who are fully vaccinated still need two weeks to achieve immunity, and the variant will continue to spread during this period.

Bettigole said: “Given its growth rate in the United Kingdom and the United States, we should expect that by late July, most infections will be Delta variants.” “This may mean that Philadelphia’s COVID cases and hospitalizations have increased significantly again. This may be possible. Means, but it doesn’t have to be.”

A health department spokesperson said that the city does not plan to immediately change the restrictions or guidelines for wearing masks, but if the number of cases in Philadelphia rises sharply and the number of hospitalizations increases, it does not rule out the re-implementation of masks.

Elsewhere, in Los Angeles County, public health officials once again It is recommended to wear a mask indoors, Regardless of the vaccination status, can prevent the spread of Delta variants.

One Axios / Ispos poll A survey released on Tuesday found that 48% of American respondents are somewhat familiar with the Delta variant. Among those who knew about this, 72% said they were a little or very worried about this variant, but only 55% of respondents said they had worn a mask all the time or part of the time when they left home. This is the lowest percentage since voting began in April 2020.

The poll included 1,065 American adults and was conducted from June 25 to 28. If there is a new COVID-19 peak in their area, only 43% of Americans say they will self-isolate, and 57% of Americans say they will stop gathering with friends and family. Another 64% said that they think the summer travel plan is not too risky.

“The United States continues to move forward,” said Cliff Young, president of Ipsos US Public Affairs. “Because of vaccines, Americans’ views of the world have changed. Vaccines and governments at all levels have said they can go out: this is a combined use.”

Topol and other health experts told Scientific American that vaccination will still be the key to preventing a more widespread COVID-19 comeback. Especially in autumn and winter As the risk of infectious diseases increases. New lockdowns and restrictions seem unlikely, so the focus will remain on strengthening vaccination. This is especially true among young people between the ages of 18 and 29—according to the CDC, this is the least vaccinated age group in the United States—and they may be more likely to spread the Delta variant in the coming months.

Topol said that the best situation in the United States is the outbreak of Delta variants in certain areas of the country. The vaccination rate in these areas is still very low, rather than the large-scale surge that occurred across the country last year and early 2021.

“We are likely to see this patchwork phenomenon,” Topol said. “Some places will light up, I hope they won’t light up too much.”