The desperation for a way to prevent the economy from collapsing under the weight of Covid-19 could mean choosing a vaccine that prevents people from really getting sick or dying but doesn't stop them from stopping to infect with the corona virus.
Although a knock-out strike against the virus is the ultimate goal, early vaccines can be limited by their delivery, says Robin Shattock, a professor at Imperial College London, who leads the development of an experimental shot.
"Is it protection against infection?" Said Shattock. "Is it protection against diseases? Is it protection against serious diseases? It is quite possible that a vaccine that only protects against serious diseases would be very useful."
As countries emerge cautiously from the barriers, leaders are looking for a preventive shot to return to life before the pandemic. Vaccines from little-known companies like CanSino Biologics Inc. from China and giants like Pfizer Inc. and AstraZeneca Plc are in development.
At least one of the fastest running experimental shots has already been tested on humans after showing effects on serious diseases – but less on infections – in animals. Experts say such a product would likely be widespread if approved, even if it is as much as it adds until a more effective version is released.
"Vaccines have to protect against disease, not necessarily infection," said Dennis Burton, immunologist and vaccine researcher at Scripps Research in La Jolla, California.
However, there are drawbacks. Michael Kinch, a drug development expert who is deputy vice chancellor at Washington University in St. Louis, may have the potential to save lives, but complacency in countries with lockdown fatigue.
"My guess would be that the day after the immunization someone would think:" I can get back to normal. Everything will be fine, "he said. "You won't necessarily realize that you are still susceptible to infection."
COVID-19 is already believed to be spread by people without symptoms, and an symptom-preventing vaccine can produce even more of them.
Vaccines are among the most effective weapons against infectious diseases and prevent up to 3 million deaths a year, according to the World Health Organization. Few, if any, are 100% effective in all people who receive them. For example, about 3% of people who receive a measles vaccine develop a mild form of the disease and can spread it to others.
In their attempts to address a rapidly growing threat, developers are turning to technologies that have never been used successfully in humans. According to the World Health Organization, more than 130 shots are in progress for COVID-19 prevention.
Vaccines work by presenting a form of the germ – or an important part of it – to the immune system that prepares the body to respond to real exposure. When this happens, immune proteins called antibodies are transferred to the virus and its entry into the cells is stopped. Sometimes vaccines raise immune T cells, which may not help prevent infection, but may slow and eventually stop their progression.
A common approach to increasing antibody levels is to inject a virus that has been inactivated or killed. Approximately nine of them are in experiments: one by China's Sinovac Biotech Ltd. produced high levels of covid-targeted antibodies in monkeys.
Another shot developed at Oxford University uses an innovative approach in which Covid genes are inserted into another harmless virus. These form proteins that are recognized by the immune system and strengthen the immune system against a real infection.
Around a quarter of the experimental shots listed by WHO, including two already in human studies, follow the same approach as the Oxford vaccine. One of the advantages of technology is its speed. AstraZeneca, which works with Oxford, has announced it will begin dispensing cans for the UK in September and next month with cans for the US, which have helped fund development.
On Saturday, AstraZeneca and four European Union countries announced that they had signed an agreement to distribute hundreds of millions of doses of the vaccine. Beijing-based Sinovac Biotech also said over the weekend that the results of human coronavirus testing test support progress towards end-stage studies.
How the shot developed by Oxford and AstraZeneca affects infections and infectivity is not yet clear. William Haseltine, a former HIV researcher at Harvard University, noted in a blog for Forbes that animals had approximately the same amount of viral genetic material, called RNA, in their systems, whether they were shot or not Not. Antibody levels against the virus are not as high as with very protective vaccines, he said.
However, clinical signs of a serious infection such as high respiratory rate and pneumonia were better in vaccinated monkeys. However, such a shot could be useful, according to Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases.
"This vaccine doesn't look like it is a knockout to protect against infection, but it could really work well for disease protection," Fauci told the medical news website Stat.
The vaccine will be a success whether it is fighting infection or serious symptoms, Pascal Soriot, AstraZeneca's chief executive officer, said in a BBC interview. The vaccine's progress to advanced studies has been approved by an independent scientific panel, and the company is waiting to see its performance, a spokesman said.
Fauci's NIAID has partnered with Moderna Inc. on a Covid vaccine test, the primary goal of which is to show that the vaccine prevents people from developing symptoms, the company said on June 11. Prevention of infections is a secondary goal.
Successful preventive measures must also prevent transmission, said Dan Barouch, a researcher at the Center for Virology and Vaccine Research at Beth Israel Deaconess Medical Center and Harvard University. Effective shots can cause some cells to become infected, but control the growth of the virus before it can be passed on to others, said Barouch, who is developing a vaccine with Johnson & Johnson. He said his efforts are aimed at a vaccine that prevents infections.
The U.S. Food and Drug Administration is considering options for a vaccine that prevents disease.
"We might consider an indication related to major disease prevention if the available data demonstrate the benefits of vaccination," FDA spokesman Michael Felberbaum answered questions. "For licensing, we would not require a vaccine to protect against infection."
Licensed vaccines, including some against whooping cough, have not been shown to protect against infection with the pathogen that causes the disease, but have been shown to protect against symptomatic diseases, Felberbaum said.
The idea of using incomplete vaccines and therapies is "okay," Kinch said. "This is just practicality. And maybe we will follow it more perfectly. There will never be a really perfect vaccine."
(Except for the headline, this story was not edited by NDTV staff and published from a syndicated feed.)