COVID-19 vaccine: Your questions answered
How long is the vaccine protective? Can vaccinated individuals spread the virus? Are the vaccines effective against COVID-19 mutations?
Ramboll health scientists answer the most pressing attendee questions from our webinar, COVID-19 Vaccine Update: A science-based overview & discussion.
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Dr. Andrea Pegoli
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Ramboll health scientists recently presented a webinar and shared science-based insights on the current vaccine landscape. Dr. Martina Vosteen,
Dr. Andrea Pegoli and Dr. Sandra Sulsky discussed the main vaccine types, how the vaccines work in the body, potential side effects, how vaccines may be distributed by geography and potential liabilities for employers.
Many questions were received ranging from how long it takes to be protected after receiving the vaccine, to whether vaccinated individuals can still spread the virus and whether the vaccines are effective against mutations. Following are several of those questions – answered by our experts.
Q: Is the COVID-19 vaccine a live vaccine?
None of the three frontrunner vaccines is live. The Pfizer and Moderna vaccines are based on mRNA technology, while the Astra-Zeneca vaccine uses an inactive adenovirus vehicle to carry the COVID-19 spike protein.
Q: How many vaccine doses are required, and are vaccinated individuals required to isolate between doses?
The three frontrunner vaccines require two doses, approximately one month apart. Symptoms noted after receiving the vaccine are mild or moderate and typically resolve after about a day. There’s no reason to isolate after receiving either dose unless a person is experiencing symptoms of COVID-19.
Q: How long is the vaccine protective?
A recently published study showed a stable immune response from the vaccine for six months. Scientists need to collect more data from vaccine trials to determine whether the vaccine will have longer-term protection.
Q: Are the authorized vaccines effective against the new SARS-CoV-2 mutations?
Pharmaceutical companies are currently investigating the efficacy of their vaccines on the mutated versions of SARS-CoV-2. Pfizer and BioNTech already announced their vaccine is able to elicit antibodies that neutralize SARS-CoV-2 with a mutation associated with rapid transmission. Additional studies are needed to assess whether the efficacy of the vaccines on these variants will be the same as originally stated by the sponsors (e.g., 95% for Moderna and the Pfizer/BioNTech vaccines).
Q: Can vaccinated individuals spread the virus?
The vaccination itself does not create an infection, and so a vaccinated person is not infectious due to receiving the vaccine. The Pfizer and Moderna vaccines appear to be about 50% effective after the first dose, with effectiveness increasing to the reported level (>90%) about two weeks after the second dose. This means that a vaccinated person may have a coincidental infection, either just before or after vaccination.
It's important to remember that the vaccines are not 100% effective, so some vaccinated individuals will remain susceptible to infection. Therefore regardless of vaccination status, it's important to continue to maintain physical distancing, mask wearing and frequent and thorough hand washing. Anyone who suspects illness or has been exposed to someone with COVID-19 should observe quarantine recommendations.
Q: Are vaccines tested for long-term effects after vaccination?
Any vaccine that receives authorization or approval for use is required to be monitored for long-term safety.
Q: Can children and teenagers be vaccinated?
The Pfizer vaccine has not yet been authorized for use in individuals under age 16, and the Moderna vaccine for use under age 18. Currently, the published prioritization schemes focus on groups at high risk of severe illness and/or exposure (i.e., elderly people and healthcare workers who treat COVID-19 patients). Later vaccine program phases will focus on successively lower risk groups, and at an even later stage (when respective data on efficacy and safety for children is available) children will be included.
Q: If a vaccine cannot guarantee protection of an asymptomatic evolution (and we continue to have positive cases counted like today), how will statistics be approached in the future?
The Pfizer and Moderna Phase 3 trials were designed to detect differences in the occurrence of symptomatic cases of COVID-19. This is an easier endpoint to detect, because the participants who become ill are easily identified, and the >90% efficacy of each vaccine was calculated on this basis. Pfizer and Moderna are currently collecting blood samples from trial participants to determine whether their vaccines are also effective against asymptomatic infections.
Q: Due to recommended vaccine storage conditions, is there risk that doses will be damaged and become ineffective?
Each vaccine must be transported and stored at its indicated temperature; otherwise, there might be the potential risk of damage. This perspective represents a main challenge for the Pfizer vaccine, which must be stored at
- 78 °C. Pfizer has developed a GPS-tracked and temperature-controlled shipper that can maintain the recommended storage conditions of its vaccine for an extended period. The shipper can maintain temperature for 10 days unopened and is equipped with a warning light indicating whether the temperature conditions were acceptable during the supply chain.
Q: Is “long COVID” prevalent across countries, and should individuals with this syndrome get the vaccine?
Investigations in several regions (e.g., US, Australia, UK, Germany) have shown the prevalence of chronic COVID syndrome, or “long COVID”. Health systems in some jurisdictions have been mobilized to create specialized clinics and provide advice to these patients. Individuals who have active COVID-19 symptoms should discuss delaying vaccination with their healthcare providers. Those who have recovered from COVID-19 within the last 90 days may be asked to delay vaccination, since they are likely resistant to reinfection during this time.
Q: Can governments mandate specific groups be vaccinated?
Quick and widespread vaccination is important in preventing the spread of COVID-19. While governments can mandate a vaccination, they rarely do. However, a collective public health interest could be favored over the individual’s interest when it comes to protection from a pandemic.
Q: What is an employer’s responsibility related to vaccination?
Employers may have the right to require vaccination but may also be required to make reasonable accommodations (e.g., changed work hours to reduce exposure to others or extended use of mask wearing or other protective equipment) for employees with a legitimate reason for refusing. Employer/employee rights and responsibilities vary by jurisdiction and should be explored with legal and human resources specialists.
Q: Could there be restricted access for people who do not get vaccinated (e.g., airlines)?
Some airlines are already looking into whether restrictions can be issued on individuals who are not vaccinated. Some governments are taking the opposite approach and increasing access to certain venues (e.g., restaurants, theaters, sports arenas) for those who have been vaccinated. The main challenge with either approach lies in maintaining secure health information and ensuring any vaccination certificate is reliable.