3 simple rules that describe the danger of Delta

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3 simple rules that describe the danger of Delta. Vaccines still outperform variant, but the unrelated world is being crushed. Fifteen months after the global closure of the new coronavirus, the pandemic still continues. Some experts estimated that by now, the world would have not one but several vaccines, with 3 billion doses already distributed.

At the same time, the coronavirus has evolved into super-transmissible variants that spread more easily. The clash between these variables will define the months and seasons to come. Again, there are three simple principles for understanding how they interact. Each one has caveats and nuances, but together, they can serve as a guide for our near future.

1. Vaccines remain variants of outcome

Vaccines have always had to grapple with variants: the alpha version (also known as B1.1. And in real-world testing, they have always lived up to their extraordinary promise. Pfizer-BioNtech and Moderna vaccines reduce the risk of symptomatic infection in more than 90 percent, as has not yet been official from Novavax.

Better yet, available vaccines reduce the chance that infected people will spread the virus by at least half or more. In the rare cases where the virus spreads, infections are usually mild, mild, and with a low viral load. As of June 21, the CDC reported only 3,907 hospitalizations and only 750 deaths among those who were fully vaccinated.

Can the Delta version (aka b.1.617.2) change that image? UK data shows that it spreads 35 to 60 percent better than Alpha, which was already 43 to 90 percent more transmissible than the original virus. (It can also be fatal, but it is not yet clear.) No longer available in the US, it causes 26 percent of new infections in the US and will soon be the cause of most of them.

But even against Delta, complete vaccination, with a great emphasis on complete vaccination, is effective. Two doses of Pfizer’s vaccine are still 88 percent effective in preventing symptomatic delta infections and 96 percent effective in preventing hospitalizations, according to a UK study. (However, a single dose is only 33 percent effective in preventing symptomatic infections.) Israel, a highly vaccinated country, is seeing a small increase in the Delta, but so far, there have been no new serious cases.

And while about 30 percent of those new cases are in fully vaccinated people, this statistic reflects, in part, the country’s success in vaccinating. Given that Israel has fully vaccinated about 85 percent of adults, it is to be expected that many new infections will occur in that large group. “Vaccines seem to hold their own against variants,” Emma Hodcroft, an epidemiologist at the University of Bern, told me. “It is something we can console ourselves with.”

But the coronavirus can cause serious problems without triggering a serious infection. Because people can develop COVID for a long time without ending up in the hospital, can Delta continue to cause long-term symptoms, even if vaccines mitigate its stinger? Anecdotal reports of long-term survivors whose symptoms subsided after vaccination may suggest otherwise, but as Harvard epidemiologist Bill Hannage told me, “we don’t know enough to say.”

Another important question that “what we really need to understand is the nature of the transmission of the success stories,” Hannez said. It is concerning that a recent study documented several cases during India’s spring surge in which healthcare workers who were fully vaccinated with AstraZeneca’s vaccine were infected by Delta and passed it on.

If other vaccines have similar vulnerabilities, vaccinated people may need to wear masks indoors to protect against the catapult of the virus in unvaccinated communities, especially during periods of high community transmission. “Unfortunately, it goes in that direction,” says Ravindra Gupta, a clinical microbiologist at the University of Cambridge who led the study. Israel has reimposed a mask mandate, while Los Angeles County and the World Health Organization recommend that vaccinated people should wear masks indoors. And such measures are understandable because …

2. Variants outnumber unvaccinated people

Regardless of the variant, vaccinated people are safer than ever. But unrelated people are at higher risk than ever because of the variant. Although they will receive some protection from the immunity of others, they tend to cluster socially and geographically, spreading outbreaks even within highly vaccinated communities.

The UK, where half the population is fully vaccinated, “could be a warning,” Hannez told me. Since the rise of the delta, the country’s cases have multiplied by six. Long-term COVID cases are likely to follow. The number of hospitalizations has almost doubled. This is not a sign that vaccines are failing. This is a sign that even highly immunized countries are home to many vulnerable people.

Delta’s presence does not mean that people without vaccines are doomed. When Alpha dominated continental Europe, many countries chose not to loosen their restrictions, and the variant did not cause a large increase in cases. “We have an agency,” Hodcroft said. “Variations make life difficult for us, but they do not determine everything.”

In the United States, most states have already fully reopened. Delta is spreading faster in counties with lower vaccination rates, whose immune vulnerability reflects social vulnerability. African Americans and Hispanic Americans are among the groups most likely to die from COVID-19, but the least likely to be vaccinated. Immunosuppressed people may not benefit from injections.

Children under the age of 12 are not yet eligible. And unlike many other wealthy countries, the pace of vaccination in the US is stagnating due to lack of access, uncertainty, and mistrust. To date, 15 states, most of which are in the South, have yet to fully vaccinate half of their adults. “See the south in the summer,” Hannez said. “That will give us the flavor that we can see in fall and winter.”

Globally, vaccine disparities are even greater. Of the 3 billion doses of vaccines administered worldwide, about 70 percent have gone to just six countries; Delta has already been detected in at least 85. While the US is concerned about the fate of states where about 40 percent of people are fully vaccinated, only 10 percent of the world’s population has reached that status. , which includes only 1 percent of Africa.

The coronavirus is now spreading in Southern Africa, South America, and Central and Southeast Asia. The year is barely halfway through, but already more people have been infected and killed by the coronavirus in 2021 than in 2020. And new ways are still emerging. Lambda, the latest recognized by the WHO, is prominent in Peru and is spreading rapidly in South America.

Many nations that have excelled in protecting their citizens now face a third threat: They have controlled COVID-19 so well that they have little natural immunity; they do not have access to vaccines; And they are surrounded by Delta. At the beginning of this year, Vietnam had recorded only 1,500 COVID-19 cases, fewer than many individual American prisons.

But now it faces a Delta-induced surge, when only 0.19 percent of its population has been fully vaccinated. Dylan Morris, an evolutionary biologist at UCLA, told me that even if Vietnam, which was so strongly on the line against COVID-19, is now bowing under the weight of Delta, “it’s a sign that the world doesn’t have that much time. “It’s possible”.

With Delta and other variants spreading so rapidly, Morris said, “my great fear is that eventually everyone will be vaccinated or infected.” He didn’t want to set a deadline, but “I don’t want to bet we have more than a year,” he said. And it would be a mistake for rich countries to think that diversity will save them, because …

3. The longer principle number 2 is, the less likely number 1 is.

Whenever a virus infects a new host, it makes copies of itself, with small genetic mutations that differentiate the new virus from its parent. As an epidemic spreads, so does the range of mutations and viruses that are advantageous allowing them, for example, to outperform their standard predecessors to spread more easily or destroy the immune system. This is how we got super-transmissible variants like Alpha and Delta. And so eventually, we can find ways that can actually infect even vaccinated people.

None of the scientists I spoke to know exactly when this could happen, but they agree that the odds decrease as the pandemic progresses. “We have to assume this is going to happen,” Gupta told me. “The more infections that are allowed, the more likely immunity will survive.”

If so, when will we know? It is the first pandemic in history in which scientists are sequencing the genes of a new virus and tracking its evolution in real time, so we know exactly about its types. Genomic monitoring can tell which mutations are emerging and laboratory experiments can show how these mutations alter the virus, that way we know which types are related. But even with this kind of work “happening at incredible speed,” Hodcroft told me, “we can’t do all the kinds of testing that we see.”

Many countries lack sequencing facilities, and those that do can easily become overwhelmed. “Over and over again, we’ve seen variants appear in places that are under exceptional stress because those variants are causing a huge increase,” Hannez said. Delta made its way through India, “but we only got it when it started causing infections in the UK.

A country that had many scientists with sequencers and little to do. So the first sign of a variant outperforming vaccines would likely be an increase in disease. “If vaccinated people start getting sick and enter hospitals with symptoms, we will have a pretty good idea of ​​what is happening,” Maia Mazumdar, an epidemiologist at Harvard Medical School and Boston Children’s Hospital, told me.

We are unlikely to be as vulnerable as at the beginning of the pandemic. Vaccines induce different types of protective antibodies and immune cells, making it difficult for a different virus to survive them all. These defenses also differ from person to person, so even if a virus breaks into a person’s ensemble, it can be disrupted when it jumps to a new host. “I don’t think that suddenly there is going to be a version that shows up and gets away from everything, and all of a sudden our vaccines become useless,” Gupta told me. “It will be incremental: With each gradual change in the virus, a part of people’s protection is lost. And people who live on the edge, vulnerable people who have not fully responded, will eventually bear the cost.”

If this happens, people who are vaccinated may need booster shots. They should be possible: mRNA vaccines made by Moderna and Pfizer should be easy to modify, especially against changing viruses. But “if we need reinforcements, I am concerned that countries that can produce vaccines will do so for their own populations, and the global gap will widen even further,” said Maria van Kerkhove of the WHO, an infectious disease epidemiologist.

The discussion of variants that outperform vaccines echoes an initial debate about whether SARS-CoV-2 will become a pandemic. “We as a society don’t think very highly of low probability events that have far reaching consequences,” Mazumdar told me. “We need to prepare for a future where we are re-launching vaccines and we have to figure out how to do better.”

Meanwhile, even highly vaccinated countries must continue to invest in other measures that can control COVID-19 but have been used improperly: better ventilation, widespread rapid tests, better contact tracing, better masks, places where people get sick. can be isolated and political. as paid sick leave.

Such measures would also reduce the spread of the virus among unvaccinated communities, creating fewer opportunities for immunity to escape. Van Kerkhove said: “I find myself breaking records that always stress all the other teams we have.” “It’s not just about vaccines. We are not using what we have.”

The WHO’s decision to name variants after the Greek alphabet means that at some point, we will probably be working with a variant of Omega. Our decisions now will determine whether that sinister name has similarly sinister qualities, or whether Omega will be just an impromptu scene during the final act of Epidemic.

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