Coronavirus vaccines: Everything we know, and dont know, so far – San Francisco Chronicle

Few things on the planet are being watched more closely than the development of vaccines for the coronavirus, which has killed 1.4 million people and infected 60 million worldwide.

In November, three drug companies developing experimental vaccines announced promising efficacy data that excited medical experts and health officials. But the good news came with a caveat: It will be months before vaccines are widely available to the public.

With a host of developments and cautions breaking over the past few weeks, The Chronicle researched the situation to obtain more clarity. Here is what we know, and dont know, about coronavirus vaccines:

Q: Are the vaccines effective?

A: Yes they are, based on the limited data released so far on three major vaccine clinical trials conducted by Pfizer and BioNTech, Moderna, and AstraZeneca and Oxford University, according to data released by the companies this month. The Pfizer and Moderna vaccines are about 95% effective, and the AstraZeneca vaccine is on average 70% effective. (The AstraZeneca vaccine is 62% effective under one dosing regimen, and 90% effective under another dosing regimen. But these results have come under some scrutiny after the company acknowledged an error in vaccine dosing given to some trial participants.) The data has not been peer reviewed. Pfizers data is final, but the other two companies data is preliminary. Pfizer is the only company to apply for FDA authorization for its vaccine.

Q: Are the vaccines safe?

A: They appear safe, based on the data thats been released. The three drug companies that have shared early results said there were no serious safety concerns among the tens of thousands of people who volunteered to participate in the trials. The Phase 3 trials enrolled 44,000 people (Pfizer), 30,000 people (Moderna) and 23,000 people (AstraZeneca).

Q: Are there any side effects?

A: Yes. A relatively small number of clinical trial participants experienced fatigue, headaches and some soreness around the injection site, though most side effects were mild or moderate and short-lived. In Pfizers trial, 3.8% of participants reported fatigue and 2% reported headaches after the second dose. Moderna said 9.7% of trial participants had fatigue, 8.9% had muscle pain, 5.2% had joint pain, 4.5% had headaches, 4.1% had pain and 2% had redness at the injection site. AstraZeneca said its vaccine did not cause any serious side effects, but unlike the two other companies, did not share details about potential mild or moderate side effects.

AstraZeneca and Johnson & Johnson both paused and later restarted their trials after a few participants reported serious illnesses a neurological illness in the AstraZeneca trial, and an unspecified serious medical condition in the Johnson & Johnson trial, but its unclear whether the problems were directly related to the vaccines.

Q: Who will get vaccinated first?

A: The highest-risk segments of the U.S. population will get vaccinated first. That will almost certainly be health care workers, first responders, and employees and residents of nursing homes. California is expected to start vaccinating 2.4 million of the states highest-priority health care workers in December, according to Gov. Gavin Newsom, most likely using the Pfizer vaccine.

Q: When will I be able to get vaccinated?

A: The vast majority of Americans will probably have access to a vaccine in the summer and fall of 2021, according to estimates from federal health officials. This wont happen all at once. The most likely scenario is that a limited number of doses will be available to health care workers in December. Then, as more doses and vaccines are manufactured, distributed and authorized, availability will gradually increase and go to other groups of people, in order of priority.

Q: How many doses will I need?

A: It depends on the vaccine. The Pfizer, Moderna and AstraZeneca vaccines are each administered in two doses. Pfizers is given 21 days apart, Modernas 28 days apart, and AstraZenecas at least one month apart. Its unclear whether partial immunity would be gained after receiving the first of the two doses, because the trials are focused on how well the vaccines work after two doses. Other vaccines, such as one being developed by Johnson & Johnson, could be administered in one dose.

Q: How many vaccines are in the pipeline?

A: There are 13 vaccine candidates in large-scale Phase 3 trials, and an additional 55 in Phase 1 or Phase 2 trials, according to the New York Times Coronavirus Vaccine Tracker. While six vaccines have been approved for early or limited use in China, Russia and the United Arab Emirates, none has received authorization in the United States. Phase 1 trials are done in a small number of people to test for safety and dosing. Phase 2 trials are done in hundreds of people to further test for safety. Phase 3 trials typically include tens of thousands of people and are the final stage of testing before a vaccine can be submitted for review by the Food and Drug Administration.

Q: Do the vaccines work well in older adults?

A: The early data suggests yes. The two vaccines that have reported more details about the demographics of their clinical trial participants, Pfizer and Moderna, indicate the vaccines work well in those 65 years and older. Pfizer said its vaccine is 94% effective in adults 65 and older. Moderna did not break out its efficacy data by age group, but about a quarter of the trial participants are 65 or older. AstraZeneca did not include details about how well the vaccine works in different age groups.

Q: Do the vaccines work well in children?

A: Its not yet known. Major clinical trials have tested the vaccines only in adults, and only recently began to expand enrollment to include teenagers and adolescents, from ages 12 to 17.

Q: How will vaccines be distributed?

A: The federal government will allocate vaccine doses to states. California will then allocate doses to local health departments, which will distribute them to health care providers. In some cases, vaccine manufacturers may send doses directly to health care providers.

Q: Where will I be able to get one?

A: Eventually, vaccines should be available at pharmacies, doctors offices and clinics. The federal government has reached agreements with CVS and Walgreens, for instance, to administer vaccines to nursing home residents. State and local officials may set up public vaccination sites, similar to the sites set up by cities and counties to do coronavirus testing and flu vaccinations.

Q: Which vaccine should I get?

A: Its too early to say. It will become more clear over time, as vaccines gain authorization and the drug companies share more details about how well each vaccine works in different age groups, ethnicities and among people who have certain health conditions. Some vaccines might work better for people 65 years and older, for instance, and others might work better for adolescents and teenagers.

The timeline of availability, and what the priority groups will look like once federal and state officials identify those groups will also factor in. The Pfizer vaccine, for example, will probably be the only one available at first, and initially those doses will go only to health care workers, first responders, and nursing home workers and residents.

Q: What are some of the hurdles to storing and transporting vaccines?

A: The Pfizer vaccine must be stored at minus-70 degrees Celsius, equivalent to minus-94 degrees Fahrenheit. Some research labs and hospitals affiliated with research institutions have ultra-cold freezers that can do this, but many rural hospitals and clinics do not. Pfizer plans to ship its vaccines in containers equipped with dry ice, and California plans to buy dozens of ultra-cold freezers to help supplement the storage and transporting of the Pfizer vaccine. Some health systems and local health departments have been buying ultra-cold freezers in anticipation of the Pfizer vaccine. The Moderna vaccine should be less difficult to manage, since it is kept at minus-20 degrees Celsius, which a standard medical freezer can accommodate. The AstraZeneca vaccine, and potentially others in the pipeline, can be kept in normal refrigerators (2 to 8 degrees Celsius) and will be easier to store and transport.

Q: Who is reviewing vaccine safety and efficacy data?

A: Each drug company has an independent data and safety monitoring board that reviews the Phase 3 clinical trial data. Once companies complete trials, they will submit the data to the FDA. The agencys Vaccines and Related Biological Products Advisory Committee will meet publicly to discuss the data. The FDAs career scientists will review the data and decide whether to grant the vaccine emergency use authorization.

In addition to the federal review, California is one of several states that has set up its own vaccine review board. Once the FDA has authorized a vaccine or vaccines, the state board made up of 11 vaccine experts, researchers and health officials will analyze the safety and efficacy of the vaccines.

Catherine Ho is a San Francisco Chronicle staff writer. Email: cho@sfchronicle.com Twitter: @Cat_Ho

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Coronavirus vaccines: Everything we know, and dont know, so far - San Francisco Chronicle