Common questions about the COVID-19 vaccines

Feeling confused or concerned? Here are some answers.


By Chris Laman, Director of Pharmacy and Cancer Center

Many aspects of the COVID-19 pandemic are unprecedented. One of those is the ongoing effort to quickly develop safe and effective vaccines against the virus that causes COVID-19. 

Chris Laman, Director of Pharmacy and Cancer Care at Columbia Memorial Hospital in Astoria, Oregon

Chris Laman, CMH Director of Pharmacy and Cancer Center

Here are answers to a few questions you may have about the Pfizer, Moderna and Johnson & Johnson vaccines.

Q: How many vaccines are in development?

A: As of March 2021, three vaccines have already been authorized for use in the U.S. (Pfizer-BioNTech, Moderna and Johnson & Johnson), and multiple others are being studied. Several have already completed phase 3 clinical trials, and others are in progress. Phase 3 clinical trials involve tens of thousands of people. They’re typically the final stage of the vaccine trial process. 

Q: Why are so many vaccines being developed at once?

A: The vaccines work in different ways. Some are based on using inactive viruses to stimulate immunity. (This is the same method used for the flu shot and many other vaccines.) Others are based on newer methods using the virus’s genetic material – either on its own or inserted into another harmless virus. Exploring different approaches gives a better chance of finding a safe and effective vaccine.

Q: When will vaccines be ready? 

A: The U.S. Food and Drug Administration (FDA) issued the first emergency use authorization for a vaccine in December, and some doses started shipping out almost immediately. It could take six months or more for a vaccine to be distributed to everyone who needs it.

Q: Who will get vaccinated first? 

A: CMH is working closely with Providence Seaside and the Clatsop County Health Department to roll out vaccines to the community according to Oregon state guidelines. Receiving the vaccine first are health care workers, first responders and residents/staff of long-term care facilities. You can read the state of Oregon’s vaccination plan at

As more doses become available, we will move into subsequent phases that include older adults, educators, essential workers and people at high risk for severe COVID-19 due to underlying medical conditions. At this time, it will likely be several months before the vaccine becomes available to the general public. If you have questions that are not answered by the Oregon Health Authority, email the Clatsop County Health Department at

Q: How will we know a vaccine is safe?

A: A vaccine must be shown to be safe and effective before it can be offered to the public – that’s what the clinical trial process is for. Phase 1 trials test a vaccine in a small number of people. Phase 2 trials test a vaccine in several hundred people. Phase 3 trials involved thousands of people who are given either the vaccine or a placebo. All of these trials assess a vaccine’s safety and how well it works. 

COVID-19 Vaccinations

Kerrie McKey, caregiver in Astoria Primary Care Clinic, receives her second COVID-19 vaccine shot in 2021.

The FDA will only approve a vaccine if it determines that the benefits outweigh the risks. The FDA continues to monitor vaccines for safety after they’re approved, including inspecting the production process and tracking reports of side effects.

Q: What does it mean when a vaccine trial is paused? 

A: A vaccine trial may be paused for safety when one or more participants have what’s called an adverse event – usually an unexplained illness. Researchers temporarily pause the trial so they can look into whether the person’s illness was random or related to the vaccine being studied. These pauses are a normal part of the clinical trial process and mean the system is working the way it should. 

Q: Will I need one shot or two? 

A: Both the Pfizer and Moderna vaccines are two-dose series. The Pfizer vaccine requires a second dose after 21 days, and the Moderna vaccine requires a second dose after 28 days. The recently approved Johnson & Johnson vaccine is a one-dose vaccination.

Q: What kinds of side effects are people reporting after receiving a COVID-19 vaccine? 

A: Side effects currently listed by Pfizer and Moderna include: 

  • After the first dose: injection site pain (2.7%)
  • After the second dose: fatigue (9.7%), muscle pain (8.9%), joint pain (5.2%), headache (4.5%), pain (4.1%) and erythema/redness at the injection site (2.0%)

These adverse events tended to be more common after the second dose but were generally short-lived, resolving within 48 hours of administration. 

Q: How much will vaccines cost?

A: The government has said COVID-19 vaccines will be provided either free or at low cost. If there is a cost to getting vaccinated, most health plans will cover it. There should be no cost to the person getting the vaccine. CMH is not charging anything for the doses it administers to the community.

Masks continue to be required at CMH for patients, caregivers, and visitors.Learn More