They infected people with Covid and discovered why there are people without a vaccine who do not get infected

They infected people with Covid and discovered why there are people without a vaccine who do not get infected
They infected people with Covid and discovered why there are people without a vaccine who do not get infected

More than four years have passed since the beginning of the Covid pandemic -in December it will be five years- and little by little the questions that this virus has been raising since its appearance are beginning to get an answer. The most recent one has just been published in the journal Nature and explains why some people get infected the SARS-CoV-2 and others do not.

The experiment was set up as a “challenge essay”carried out by University College London, the Wellcome Sanger Institute and Imperial College London, in the United Kingdom. HIV-negative young adults between 16 and 30 years old, who had never received a dose of a Covid vaccine, were inoculated by intranasal route a strain of the virus in a controlled environment. And it was observed what was happening.

“Before the challenge, volunteers underwent a thorough evaluation to exclude risk factors for severe disease and eliminate the confounding effects of comorbidities,” the Nature article says. “We studied local and systemic immune responses at single-cell resolution in 16 participants“,” the researchers explained.

The highly controlled nature of the experimental model allowed measurements to be made the day before inoculation. This was followed by detailed analyses of the cellular responses after inoculation and subsequent infection, both systemically in the blood as locally in the nasopharynxto decipher antiviral responses against SARS-CoV-2 in a precise and temporal manner.

After inoculation, six participants developed a sustained infection of Covid. Three others produced multiple PCR tests sporadic and borderline positive between day 1.5 and day 7 after inoculation and were considered “transient infection”. The remaining seven participants remained negative to PCR testing throughout the period, indicating that these individuals successfully avoided the onset of sustained or transient infection.

The people who participated in the research had not been vaccinated against Covid. Photo: AP

How the body reacted in each case

“To comprehensively identify and temporally graph responses to SARS-CoV-2 exposure in these phenotypically divergent groups, we performed single-cell RNA sequencing,” the scientists say, and verified how the antibodies responded at seven points in time.

“Inspired by the identified and potentially protective responses in cases of non-sustained infection immediately after inoculation, we next set out to identify genes for which pre-infection expression levels could predict disease outcome. The day before viral inoculation, HLA-DQA2 expression in immune and nasopharyngeal blood cells Was greater in participants in whom the virus failed to establish a sustained infection,” they revealed.

Finally, they stated: “Our data suggest that HLA-DQA2 expression is indicative of protection against productive SARS-CoV-2 infections, which we confirmed by cross-validation and in our independent validation cohort. To the best of our knowledge, this is the first predictor derived from genetic expression that is not based on acquired immunological memory.”

What is the use of this research? They explained in The Conversation: “Our study has important implications for future treatments and vaccine development. By comparing our data with volunteers who have never been exposed to the virus with those who already have immunity, we can identify New ways to induce protectionwhile helping to develop more effective vaccines for future pandemics.”

The mystery of long Covid

Another of the questions of the pandemic whose answer has been sought in recent times is why some people develop Long Covidthat is, people who sustain over time sequelae of the diseaseTwo investigations on this subject have been reviewed in recent days in the journal Science.

Symptoms of long Covid have been described in both adults and children.

People with persistent Covid-19 conditions may manifest a wide variety of symptomsranging from mild to severe, and can resemble symptoms of other diseases. They can last for weeks, months, or years after contracting the virus. The most common symptoms are: fatigue, brain fog and general malaise post-effort, but have been identified more than 200 associated symptoms.

The main suspicion is that antibodies in the blood attack the patient’s own tissues. Both working groups, one led by immunologist Akiko Iwasaki at Yale University, and the other by immunologist Jeroen den Dunnen at the University Medical Center in Amsterdam, injected mice with antibodies from the blood of people with long-term Covid-19.

They concluded that in some cases the rodents developed symptoms that seemed to reflect those of their human donors, in particular a heightened sensitivity to pain. Some scientists say these studies reinforce the idea that a dysfunctional immune systemtriggered by a coronavirus infection, fuels the symptoms of long Covid, and they say this, too, opens the door to potential new treatment trials.

 
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