Gold diggers in French Guiana, revelers in Cape Cod, and Indian caretakers: although they live in different corners of the world, they have two things in common. All were vaccinated against COVID-19 and all became part of new infection clusters. In the past few weeks, cases like this have shown that corona transmission chains and superspreading can occur even in groups where almost everyone has received the vaccine.
This not only triggered the alarm from the health authorities, but also torpedoed hopes for a quick return to normalcy in the United States. This is because of health investigators’ findings from an outbreak in Provincetown, a coastal town on Cape Cod on the east coast that saw a boisterous parade and weeks of overcrowded pool parties in early July. Since then, according to the health authorities more than 500 cases of COVID-19 that are associated with these events. 73 percent of them were vaccinated.
The outbreak in Provincetown was caused by the Delta variant, which – like in Europe – is now responsible for most cases in the USA. According to CDC director Rochelle Walensky The “decisive discovery” is that vaccinated people appear to have as much virus in their bodies as unvaccinated people – at least there is initial data to suggest this. That seems to have given the Centers for Disease Control, the highest disease protection authority, a real scare.
Infections in a gold mine with Biontech
For weeks now, studies around the world have been showing evidence of outbreaks in people who have been vaccinated. So described a scientific team in Paris and French Guiana recently how COVID-19 was rampant in a South American gold mine in May, even though almost all miners had received the Biontech Pfizer vaccine. Despite the immunization, 60 percent of them became infected with another variant – here it was Gamma. This surprised the scientists so much that they checked whether the vaccines had been damaged in transit. But that was not the case.
The first studies with the Biontech-Pfizer vaccine, which is most commonly used in the USA and is also the most popular product in Germany, had shown that it prevented symptomatic diseases with more than 90 percent effectiveness. But it was completely different with the gold diggers, because half of them fell ill with symptoms such as fever. The vaccine may still have helped, and that’s the good news: none of the miners got seriously ill, even though most of them were over 50 years old and had some risk factors such as high blood pressure and diabetes.
Other vaccinated superspreading events occurred in India, where healthcare workers could get the AstraZeneca vaccine from early 2021. When a British-Indian research team investigated the COVID-19 cases there, They found A significant number of so-called breakthrough infections among vaccinated people in three hospitals in Delhi, including a super-spread that infected 30 people.
Delta tends to breakthrough
The breakthrough infections are much more likely with the Delta variant than with one of the older strains, according to the researchers. The older variants were never able to cause an accumulation of more than two related cases among healthcare workers. However, the researchers found ten such delta eruptions.
The fact that the variant is more easily transferable could be one of the reasons that this strain may “escape” the immune system, say the researchers. This could explain the outbreaks in vaccinated people and also means that it is easier to get infected again, even if you have already had COVID-19. The British-Indian team estimate that natural protection against the infection is cut in half when people are exposed to the Delta virus.
In the United States, the Provincetown outbreak may have occurred during Independence Week around July 4th, when the city received thousands of visitors. In the same month, the investigators learned, according to a US media published CDC presentation out of a hundred COVID-19 cases. Sequencing labs in Boston found it was caused by the Delta variant. The Provincetown outbreak raised the alarm bells at the CDC because vaccines did not appear to prevent the virus from being transmitted from person to person here, even though most were vaccinated . The CDC presentation also made the amazing statement that Delta is equally contagious like chicken pox be.
Virus amount does not change
Another important clue came from PCR tests performed on approximately 200 people from the Provincetown cluster. The amount of the virus in a person’s airways – and thus what they could put into the world every time they cough and sneeze – was about the same whether they were vaccinated or not.
But that does not prove – and this is important – that vaccinated people transmit just as many viruses, says Monica Gandhi, who researches infectious diseases at the University of California in San Francisco. This is because PCR tests detect both virus fragments and live pathogens, so that vaccinated people may excrete fewer live viruses or remain infectious for a shorter period of time. Gandhi adds that despite the various variants, the vaccines are still effective and prevent most serious illnesses. Nevertheless, “we see more mild, symptomatic cases,” she says – and also transmission among vaccinated people. This, in turn, actually results from the fact that the current vaccines are not sterilizing, i.e. the transmission of viruses is not automatically prevented.
The delta problem poses a problem for the CDC: as recently as May, the authority had told vaccinated Americans that they no longer needed to wear masks indoors, and this advice was followed in many shops and in public places. In view of the new events, however, the epidemic protection authority has been turning around and has been recommending, since the beginning of August, that those who have been vaccinated should again protect themselves with a mask if no distance is possible.
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