The Race to Develop a Covid Vaccine

It is not enough to know that a candidate vaccine produces an antibody response — even a vigorous response — in susceptible people or that hundreds of volunteers inoculated with it experienced no serious adverse effects. Not until a vaccine is tested in tens of thousands of people can doctors be reasonably certain it is safe and effective, and sometimes not even then.

Under normal circumstances, this process takes years. But these are not normal times, so the testing of potential Covid-19 vaccines is being collapsed into months, which could increase the risk of foul-ups. However, Dr. Francis Collins, director of the National Institutes of Health, gave his word that, despite being in a hurry to get an effective vaccine to the public, “we will not compromise on safety.”

Here’s how Dr. Offit, who is involved in supervising the Covid vaccine trials, described the necessary sequence of events:

A prospective vaccine is first tested on laboratory animals that normally develop Covid-19 when infected with the virus, such as mice, to see if it prevents the disease. This is called “proof of concept” that the vaccine can work. It is followed by Phase I and Phase II trials in perhaps hundreds or thousands of human volunteers. Researchers look for evidence that the vaccine is safe, and test different vaccine doses to find one that best results in antibodies that could protect against the virus. At least two vaccine candidates are already in this stage.

Now comes the big test, Phase III, a prospective placebo-controlled trial of tens of thousands of individuals to assess both safety and effectiveness. For one or more of the five promising Covid vaccine candidates being fast-tracked, this stage is expected to start in July. Each Phase III trial will entail 20,000 people who get the experimental vaccine and a control (placebo) group of 10,000 unvaccinated people. The trials will take place in areas here and abroad that are already, or expected to be, “hot spots” for Covid infections.

But depending on how prevalent the virus is this summer where the trials take place, it could take months — or even a year — to determine how well the vaccine prevents disease.

“That’s the only way to know if the immune response seen in earlier trials is protective in the real world,” Dr. Offit said. “If there’s little disease over the summer, it could be a problem. We may have to keep recruiting participants until enough people in the placebo group got sick to have a meaningful comparison with the vaccinated group. We can’t short-circuit the process.”

  • Updated June 22, 2020

    • Is it harder to exercise while wearing a mask?

      A commentary published this month on the website of the British Journal of Sports Medicine points out that covering your face during exercise “comes with issues of potential breathing restriction and discomfort” and requires “balancing benefits versus possible adverse events.” Masks do alter exercise, says Cedric X. Bryant, the president and chief science officer of the American Council on Exercise, a nonprofit organization that funds exercise research and certifies fitness professionals. “In my personal experience,” he says, “heart rates are higher at the same relative intensity when you wear a mask.” Some people also could experience lightheadedness during familiar workouts while masked, says Len Kravitz, a professor of exercise science at the University of New Mexico.

    • I’ve heard about a treatment called dexamethasone. Does it work?

      The steroid, dexamethasone, is the first treatment shown to reduce mortality in severely ill patients, according to scientists in Britain. The drug appears to reduce inflammation caused by the immune system, protecting the tissues. In the study, dexamethasone reduced deaths of patients on ventilators by one-third, and deaths of patients on oxygen by one-fifth.

    • What is pandemic paid leave?

      The coronavirus emergency relief package gives many American workers paid leave if they need to take time off because of the virus. It gives qualified workers two weeks of paid sick leave if they are ill, quarantined or seeking diagnosis or preventive care for coronavirus, or if they are caring for sick family members. It gives 12 weeks of paid leave to people caring for children whose schools are closed or whose child care provider is unavailable because of the coronavirus. It is the first time the United States has had widespread federally mandated paid leave, and includes people who don’t typically get such benefits, like part-time and gig economy workers. But the measure excludes at least half of private-sector workers, including those at the country’s largest employers, and gives small employers significant leeway to deny leave.

    • Does asymptomatic transmission of Covid-19 happen?

      So far, the evidence seems to show it does. A widely cited paper published in April suggests that people are most infectious about two days before the onset of coronavirus symptoms and estimated that 44 percent of new infections were a result of transmission from people who were not yet showing symptoms. Recently, a top expert at the World Health Organization stated that transmission of the coronavirus by people who did not have symptoms was “very rare,” but she later walked back that statement.

    • What’s the risk of catching coronavirus from a surface?

      Touching contaminated objects and then infecting ourselves with the germs is not typically how the virus spreads. But it can happen. A number of studies of flu, rhinovirus, coronavirus and other microbes have shown that respiratory illnesses, including the new coronavirus, can spread by touching contaminated surfaces, particularly in places like day care centers, offices and hospitals. But a long chain of events has to happen for the disease to spread that way. The best way to protect yourself from coronavirus — whether it’s surface transmission or close human contact — is still social distancing, washing your hands, not touching your face and wearing masks.

    • How does blood type influence coronavirus?

      A study by European scientists is the first to document a strong statistical link between genetic variations and Covid-19, the illness caused by the coronavirus. Having Type A blood was linked to a 50 percent increase in the likelihood that a patient would need to get oxygen or to go on a ventilator, according to the new study.

    • How many people have lost their jobs due to coronavirus in the U.S.?

      The unemployment rate fell to 13.3 percent in May, the Labor Department said on June 5, an unexpected improvement in the nation’s job market as hiring rebounded faster than economists expected. Economists had forecast the unemployment rate to increase to as much as 20 percent, after it hit 14.7 percent in April, which was the highest since the government began keeping official statistics after World War II. But the unemployment rate dipped instead, with employers adding 2.5 million jobs, after more than 20 million jobs were lost in April.

    • My state is reopening. Is it safe to go out?

      States are reopening bit by bit. This means that more public spaces are available for use and more and more businesses are being allowed to open again. The federal government is largely leaving the decision up to states, and some state leaders are leaving the decision up to local authorities. Even if you aren’t being told to stay at home, it’s still a good idea to limit trips outside and your interaction with other people.

    • What are the symptoms of coronavirus?

      Common symptoms include fever, a dry cough, fatigue and difficulty breathing or shortness of breath. Some of these symptoms overlap with those of the flu, making detection difficult, but runny noses and stuffy sinuses are less common. The C.D.C. has also added chills, muscle pain, sore throat, headache and a new loss of the sense of taste or smell as symptoms to look out for. Most people fall ill five to seven days after exposure, but symptoms may appear in as few as two days or as many as 14 days.

    • How can I protect myself while flying?

      If air travel is unavoidable, there are some steps you can take to protect yourself. Most important: Wash your hands often, and stop touching your face. If possible, choose a window seat. A study from Emory University found that during flu season, the safest place to sit on a plane is by a window, as people sitting in window seats had less contact with potentially sick people. Disinfect hard surfaces. When you get to your seat and your hands are clean, use disinfecting wipes to clean the hard surfaces at your seat like the head and arm rest, the seatbelt buckle, the remote, screen, seat back pocket and the tray table. If the seat is hard and nonporous or leather or pleather, you can wipe that down, too. (Using wipes on upholstered seats could lead to a wet seat and spreading of germs rather than killing them.)

    • What should I do if I feel sick?

      If you’ve been exposed to the coronavirus or think you have, and have a fever or symptoms like a cough or difficulty breathing, call a doctor. They should give you advice on whether you should be tested, how to get tested, and how to seek medical treatment without potentially infecting or exposing others.

He expects that the vaccine would have to be at least 70 percent effective to roll it out for mass use. But even then, he added, “we wouldn’t know for many more months how long immunity would last.” He cautioned against undue optimism about how good an approved vaccine will be. He said a vaccine might be considered acceptable if it prevents severe disease but not most or all infections that cause no symptoms or only mild illness.

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