The covid-19 vaccine, based on a chimpanzee virus, generates a strong immune response.
OXFORD England (El Pais) – One of the most advanced experimental vaccines against covid-19, is developed by the University of Oxford. The vaccine offers hopeful results to be able to stop the plague of the new coronavirus. According to data from its first human trial, the injection generates a strong immune response without causing severe adverse effects, published on Monday in the medical journal The Lancet. The tests, which began in April, have involved more than 1,000 healthy volunteers in the United Kingdom.
The experimental vaccine is made from a weakened version of an adenovirus of the common chimpanzee cold. The virus is genetically modified to prevent its multiplication and add genes with instructions to make only the proteins of the coronavirus spicule. The bumps that give it its characteristic medieval mace shape and that also serves as a key to enter human cells.
These foreign proteins generated by the vaccine train the immune system and, as the new results show, cause the creation of a double barrier: neutralizing antibodies, which block the foreign particles, and T lymphocytes, a type of white blood cell that destroys the infected cells. These defenses were maintained almost two months after the start of the study.
The goal of this first trial of more than 1,000 people aged 18 to 55 was to rule out possible serious adverse effects, adjust the dose, and measure the vaccine’s immune response. The University of Oxford and the British pharmaceutical company AstraZeneca have already begun a final trial with tens of thousands of people to certify that the vaccine is safe and prevents disease. The project has begun testing with about 15,000 people in the U.K., but the current shortage of infections in the region makes it difficult to prove that the vaccine protects. Oxford has announced another trial with 5,000 volunteers in Brazil and another with 2,000 in South Africa.
Pharmaceutical company AstraZeneca has pledged to supply 400 million doses to the E.U., warning that it may not work in full. Sarah Gilbert, the research leader, said in April that her team had achieved in three months what usually takes five years, thanks to their previous work with another coronavirus, the Middle East Respiratory Syndrome (MERS). Gilbert’s three children, 21-year-old triplets studying biochemistry, have been involved in the first trials of their mother’s experimental vaccine, the Oxford professor said in a recent interview with Bloomberg Businessweek magazine.
“There is still a lot of work to be done before we can confirm that our vaccine will help address the covid-19 pandemic, but these initial results are promising,” Gilbert acknowledged in a statement Monday. The researcher and her team recognize the limitations of their study: it does not include older people or patients with other relevant diseases, or diverse populations from different countries. Ninety-one percent of the 1,077 participants in this first trial were white, with an average age of 35. The tests that are currently being conducted with tens of thousands of people seek to address these shortcomings.
Gilbert also admits to other significant gaps. “We still don’t know how strong the immune response has to be to ensure effective protection against SARS-CoV-2 infection,” she said.
The virus is no longer the same as that spread around the world from the Chinese city of Wuhan. According to some preliminary studies, the original variant has been replaced almost everywhere on the planet by another with a characteristic mutation that could increase the viral load in patients. “What is alarming is that vaccines would need to generate higher levels of antibodies if the levels of the virus are much higher. And that could be a big problem,” Spanish biologist David Pulido Gomez, who is working at Oxford on the development of the vaccine, told this newspaper in early July.
“There is a lot of work to be done before we can confirm that our vaccine will help address the pandemic of covid″, acknowledges researcher Sarah Gilbert.
Pharmacist AstraZeneca itself acknowledges that the vaccine may not finally work, but has already committed to manufacturing more than two billion doses, with 400 million doses for the E.U. due to start arriving later this year. The company – which is responsible for drugs such as omeprazole, which treats heartburn – has said it will make the vaccine more readily available during the pandemic without seeking financial gain.
AstraZeneca has also announced similar agreements with the U.S. and the U.K. The Coalition for Innovations in Epidemic Preparedness – the EIPC, founded by the governments of Norway and India, the Bill & Melinda Gates Foundation, the Wellcome Trust and the World Economic Forum – will invest 335 million to manufacture another 300 million doses within the ACT Accelerator, an international consortium supported by the WHO and the E.U. to obtain vaccines “in record time.” AstraZeneca has signed another agreement with India’s Serum Institute, one of the world’s largest vaccine manufacturers, to produce 1 billion doses for low- and middle-income countries, with a commitment to supply 400 million by 2020.
The first trials of the experimental Oxford vaccine in macaques had produced bittersweet results. Monkeys vaccinated and subsequently infected did not develop pneumonia. Still, they did have the virus in their throats, which could mean that the vaccine prevents the more severe forms of the disease, but not its transmission.
Spanish veterinarian Javier Salguero, who participates in the monkey trials at the government’s public health agency Public Health England, believes this effect observed in macaques may be due to the design of the experiments that are very different from real-world conditions. The animals are inoculated with the coronavirus at very high doses and by multiple routes. “Full protection in this animal model is tough to achieve, but it may be achieved in humans. People are not infected with very high doses or by intratracheal route,” explained Salguero in an interview with this newspaper.
According to the WHO registry, the experimental Oxford vaccine is one of 23 different prototypes already being tested in humans around the world. The U.S. company Moderna has announced that it will begin a trial with 30,000 volunteers on July 27 to test its candidate, which has shown promising results in the first trial with 45 people. China, with several advanced experimental vaccines, has already approved one for use in the military.
