In the past few weeks, the Delta coronavirus variant has Shattered hope Many Americans look forward to celebrating the “hot summer” and the end of the pandemic.
As a health expert June warning, The highly contagious Delta variant has been hit particularly hard in states with low vaccination rates. Fill up hospitals and morgues Back again to the darkest days of the pandemic. Unlike previous variants, new data shows that some vaccinated people infected with Delta—although they have overwhelming protection against serious diseases—can still transmit the virus to other people.This led the CDC to recommend vaccination in areas with high virus transmission Should resume wearing masks In indoor public places.
The big problem still exists Regarding the extent to which “breakthrough” cases spread Delta. But now people are increasingly worried that Delta Air Lines will become an unstoppable force.
However, the message from experts who watched the Delta wave in Europe is even more encouraging, showing that the usual rulebooks still apply: strategies such as vaccination and wearing masks in indoor public places and avoiding crowds can reduce the number of cases.
At the same time, some observers Watch what happened With Delta in the United Kingdom and India, the variant was first discovered there, and it is speculated that the suffering of Delta in the United States may lie in At least short-lived, No matter what we do to limit its spread. In these two countries, the sharp rise in cases followed a similar rapid decline, which suggests that the rapidly spreading Delta variants usually die out on their own very quickly.
There are two big problems with this view. First of all, if we let Delta Air Lines go with the flow, the cost of life and overburdened hospitals will be high.
Lauren Ancel Meyers, a computational epidemiologist at the University of Texas at Austin and the director of the research center, said: “In the process of reaching this point, the number of hospitalizations will be a disaster. Sexual.” UT COVID-19 Modeling Alliance, Tell BuzzFeed News. “You will overwhelm your healthcare system.”
Second, if you look at the diversity of Delta curves seen throughout Europe, it is difficult to determine whether there is a typical fast burning Delta wave. In countries that have experienced rapid rise and decline, changes in people’s behavior—rather than the inherent characteristics of delta variables—seem to be an important part of reversing the situation.
Digging deeper into the reasons behind the different Delta waves appearing throughout Europe, a more promising message emerged: Although terrible, Delta variants seem to be controllable. Vaccination is our best weapon, but moderate social distancing measures that are effective against other less spreading coronaviruses are still very helpful.
Triangle wave of selected countries
Comparison doesn’t make much sense India’s catastrophic delta wave Experts say it’s the same as those in the United States, Britain, and other European countries.India not only has a large population Basically not vaccinated At that time, the Delta variant destroyed the country in April and May, but monitoring and testing were so incomplete that it was not clear whether the recorded new case curve accurately reflected how many people were infected.
But if you look at the delta waves seen so far in European countries and the United States, the curves are very different. In the above chart, only the United Kingdom and the Netherlands have a faster rise and fall, while other countries have a slower rise. In Germany, the Delta curve is just a flash in the pan.
Although the United Kingdom was exposed to Delta variants earlier than other countries, mainly due to people traveling to and from India, the time when Delta established its dominant position cannot explain the differences in other countries.
It is difficult to sort out the exact reasons for the differences between delta waves in European countries. But transmission will depend on the number of people with a certain degree of immunity—whether through vaccination or previous coronavirus infections—and the behavioral patterns that encourage transmission.
Among the countries shown, France has the lowest vaccination rate, with 49% of its population fully vaccinated (the United States is slightly higher at 50%). At the same time, the UK has the highest vaccination rate, with 57.3% of the population being vaccinated. The other European countries shown are tightly squeezed between 53.2% and 54.2%. Therefore, the degree of vaccination does not seem to explain the huge differences in the Delta curve between countries.
One clue that differences in people’s behavior play an important role is that Germany retains Tighter social distance control Compared with most European neighboring countries, people who cannot live together are required to maintain a distance of 1.5 meters (about 5 feet) and wear medical masks in public transportation and shops.
At the same time, looking at these two countries that have experienced the rapid rise and fall of cases caused by delta mutations provides a strong hint that large-scale crowd gatherings have played a huge role in every wave.
How football tournaments are driving the British delta wave
Britain’s surge seems to be due to Euro 2020 Fans crowded into bars and homes to watch the game. In England and Scotland, within a week or two after the respective teams played their first games, the increase in new cases increased sharply, but only reversed within a few weeks after each team withdrew.
The Scotland team was eliminated early. But in the finals of England, the viewing party lasted until July 11.
If the rallies to watch the game strongly promote the delta wave, then the peak time that follows is exactly what epidemiologists expect. Paul Hunter, an epidemiologist at the University of East Anglia in the UK, told BuzzFeed News: “It will take two weeks for the signal to clearly appear in the data.”
Unlike the previous surge in the UK, the cases were predominantly male, in line with the demographics of people watching the game.And one New research Researchers from the Scottish Department of Public Health have reinforced the view that the obvious delta peak in the UK is mainly due to the interruption of social distancing during the tournament viewing party. The researchers pointed out: “During the peak period, more than half of the reported cases in Scotland either participated in the events of Euro 2020 or were close contacts of those who participated.”
Most of the infected people are very young and have not developed serious illnesses. Coupled with the rapid progress in vaccination in the UK in the past few months, this means that the peak hospitalization period is less than one-fifth of the peak period of Alpha variants that appeared in the UK in January. Although the number of COVID deaths has increased slightly, only about 90 people die from the disease every day in the UK, and more than 1,200 people die from the disease at the peak of the Alpha wave.
The rapid and good transfer of British cases. Some experts are puzzled. They originally expected the infection to soar to new heights after “Freedom Day” on July 19, when British Prime Minister Boris Johnson lifted the remaining coronavirus restrictions in England and allowed bars. And restaurants are open as usual and all mask requirements are cancelled.
Although Neil Ferguson, a disease modeler at Imperial College London, had predicted new cases May increase to 200,000 per day, The 7-day rolling average of new cases reached a peak around the free day, less than 50,000 cases per day, and then began to decline.In the past few days, the decline in the number of cases seems to have plateaued, and Not sure Where did the delta wave in the UK come from.
Another European country where the number of cases is clearly rising and falling is the Netherlands. About 10 days after the Dutch government lifted almost all remaining coronavirus restrictions on June 26, cases began to surge. Tom Wenseleers, a biostatistician and evolutionary biologist at the Catholic University of Leuven in Belgium, told BuzzFeed News: “This is indeed the peak of cases among young people.” As in the UK, this did not translate into a significant increase in hospitalizations or deaths. .
Even so, on July 9, the country suddenly changed its direction, closing nightclubs, and restricting designated seats in bars and restaurants to 1.5 meters apart.The Dutch government stated: “Most infections occur in nightlife venues and large gatherings. In the statement Announce new restrictions.
The Dutch delta wave reached its peak within two weeks after the new restrictions took effect. If this rapid transition is indeed driven primarily by nightclub closures, it provides another encouraging message that the Delta variant can be controlled through more subtle changes in behavior rather than complete lock-in.
“Britain and the Netherlands should be advisors against despair,” Bill Hanach, an epidemiologist at Harvard University’s Chen Zengxi School of Public Health, told BuzzFeed News. “We don’t have to be fatalistic about Delta variants.”
Hanage is not the only one who believes that the experience of European countries shows that moderate precautions such as wearing masks in public indoor spaces and avoiding large gatherings can have a significant impact in the face of Delta variants.
Meyers said: “When behavior changes, regardless of whether there is an official policy change to protect you from infection, we will see this shift.”
Delta wave and COVID vaccinations in U.S. states
As shown in the figure above, so far, states with lower vaccination rates tend to experience more severe delta waves.
Therefore, in the long run, boosting vaccination in places where few people have been vaccinated remains the best hope for defeating the Delta variant in the United States.But although the vaccination rate is Fastest growing In states currently experiencing the worst delta surges, there is still a long way to go-people who are vaccinated for the first time today will not receive strong protection for a few weeks.
At a White House press conference on Thursday, when asked what the United States needs to do to combat the delta wave, Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases, supported the view that it would help reverse The previously surged control measures will work again.
Fauci said: “You can do this right now with mitigation measures.” “Mitigation measures are everything you hear from the CDC’s recommendations, including wearing masks and avoiding crowded situations, so as not to increase the ability to spread the virus.”
“The final outcome of all this is vaccination,” Fauci added. However, if the United States can reduce transmission in the short term and increase vaccination rates in the long term, he said, “We will reverse the delta’s surge. I assure you that will happen.”