Breakthroughs in vaccination under Delta variant: How infectious are vaccinated people?

Breakthroughs in vaccination under Delta variant: How infectious are vaccinated people?
Breakthroughs in vaccination under Delta variant: How infectious are vaccinated people?

Vaccinations are intended to protect against a serious disease course after a corona infection. But breakthrough infections are increasingly observed. Do vaccinated people carry the infection on?

That even people who have been vaccinated twice with the Coronavirus infect is well known and causes a lot of uncertainty. One thing is clear: with a complete vaccination the risk of serious illness or even death decreases massively. But the vaccines are less effective in protecting against one infection.

The Israeli Ministry of Health recently announced that the effectiveness of the Biontech / Pfizer vaccine used in Israel had declined sharply since the beginning of June. According to the ministry, the vaccination only prevents corona infection by 39 percent and serious illnesses by 91 percent. At the same time, the more contagious one is spreading in the country Delta-Variant.

Data from mid-July this year also suggested that the vaccines might become less effective over time. Since the beginning of August, Israel has been vaccinating all those over 60 years of age who received the second vaccination at least five months ago for the third time.

It is not clear whether the infection rate among vaccinated persons will then decrease. The fact that people with a double vaccination dose can pass on the virus and thus also endanger others makes fighting pandemic more difficult, especially with the more contagious Delta variant.

How common are vaccination breakthroughs?

People develop different immune responses to vaccination. Elderly or previously ill people in particular often do not provide adequate immune protection. There is no 100 percent protection with vaccinations. It is therefore clear: the more people are vaccinated, the more breakthrough infections there are in relative terms.

That Robert Koch Institute (RKI) has listed a total of 8,715 vaccination breakthroughs since February 2021 (as of August 5, 2021). As many Infections run asymptomatic, a higher number of unreported cases can be assumed.

The agency also assumes that the effectiveness of the vaccines is reduced by the more contagious Delta variant. It should be around 87 percent for those over 60 and 88 percent for those aged 18 to 59.

How are the disease processes?

Of the more than 8,700 reported and confirmed breakthrough infections, 808 had to be treated in hospital. It can be assumed that these are people who have not been able to develop adequate immune protection due to old age or certain previous illnesses.

The numbers in Great Britain are more dramatic: of over 300,000 infections that were determined here with the Delta variant of the virus, 47,000 people were double-vaccinated. 670 people died, 402 of them both had vaccine doses. 389 of them were over 60 years old.

Other, smaller studies, for example in Israel, are also tracking down the phenomenon. As of May 20, 2021, the researchers from Ashdod examined the data of 152 Covid-19 patients who had to be hospitalized. The vaccination campaign in the country started about six months earlier, by which time 5.4 million Israelis had already been double-vaccinated. The study only examined the data from 17 clinics. How often vaccination breakthroughs actually occur remains unclear.

The analysis showed that only six percent of the patients with severe vaccination breakthroughs were previously healthy. All others (146) struggled with at least one previous illness. 71 percent suffered from high blood pressure, 48 percent under Diabetes, 32 percent had chronic kidney failure. Heart failure, lung disease, cancer and dementia were also among the diagnosed pre-existing conditions.

How infectious are vaccinated people?

The previously approved vaccines against SARS-CoV-2 do not produce so-called sterile immunity. That means: people who have been vaccinated can pass the virus on. So far, however, the thesis has been that they do not develop as high a viral load as those who have not been vaccinated, i.e. that they are much less contagious. But more recent data suggest otherwise.

The British public health authority “Public Health England” (PHE) published a statement which suggests that people infected with the Delta variant are very contagious – regardless of whether they are vaccinated or not. According to the report, the viral load in vaccinated people who tested positive after a breakthrough infection is just as high as in unvaccinated people. This makes them highly contagious in the first few days after infection.

This also emerges from the analyzes of the US disease protection agency “Centers for Disease Control and Prevention” (CDC). A virus outbreak was being investigated on July 4th in Massachusetts. Of the 469 infections found on the Cape Cod peninsula, three quarters were fully vaccinated. From the distribution of the cases, the researchers apparently concluded that vaccinated people who become infected are similarly infectious to those who have not been vaccinated. They can carry a similarly high viral load.

Apparently, this only applies to the first few days after infection. At least that is what analyzes from the National Center of Infectious Diseases in Singapore suggest. After that, the viral load drops significantly faster in vaccinated people than in unvaccinated people.

What do experts advise?

The chairman of the World Medical Association, Frank Ulrich Montgomery, spoke out against the background of vaccination breakthroughs last weekend in favor of compulsory testing for all travelers returning from abroad. All those entering, without exception, would have to present a negative corona test, “including those who have been vaccinated and those who have recovered,” said Montgomery to the newspapers of the “Funke Mediengruppe”.

The epidemiologist Markus Scholz from the University of Leipzig also believes it makes sense to test people who have been vaccinated outside the travel season: “The vaccination protects 90 percent against a serious course of the disease, but only 60 to 80 percent against infection”, he explains in an interview with t-online. “This means that vaccinated people can also be virus carriers. That also means: the more infection is allowed, the more vaccinated people and thus risk groups will be affected.”

And Carsten Watzl, Secretary General of the German Society for Immunology, believes that tests of vaccinated people make sense in certain situations: “With the number of vaccinations, the number of breakthrough infections also increases,” Watzl told dpa. “This is indeed reduced, but depending on how the vaccination worked for me and the viral load my counterpart is carrying, it can happen that I become infected as a vaccinated person.” It could then be dangerous, especially for older people and those with previous illnesses.

His advice: If vaccinated and unvaccinated people want to meet privately, like at a garden party, they should get tested before such a meeting. Because whenever vaccinated and non-vaccinated people meet, the risk of infection also increases for those who have been vaccinated. “Since it is not always clear who has what pre-existing illness, for example, it is easiest if everyone can be tested beforehand.” Citizen quick tests are a little more careful than the self-test for at home, but both are sufficient.

Dr. Ulrich Lauer from the University Hospital Tübingen calls for the development of new vaccines: “At the moment we only have first-generation vaccines”, he explained in an interview with t-online. “These were developed under the premise of being able to be approved as quickly as possible and accordingly initially had to ‘only’ fulfill the requirement to protect against serious disease progression and death in connection with Covid-19 disease. This goal they usually achieve it very well, because people who become infected despite a complete vaccination usually do not become seriously ill and only very rarely die. that are currently still based on double vaccinations, slow down in an efficient way. “

He is researching a nasal spray vaccination. The first clinical studies are planned for the next year.

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