Dance of the porcupines: A view into the rapid development of covid-19 vaccines from around the world
February 8, 2021
Coronavirus Update FAQ 10
April 8, 2021



This is the ninth of a series of Covid-19 newsletters from FDIME (Foundation for the Development of Internal Medicine in Europe). The aim of the newsletters is to present qualified answers to the public, specifically on issues in which internists have a saying.
This newsletter has been written by Verena Briner and concerns questions, which were sent to her.
FDIME is a non-profit organizations, which aims to improve medical care for patients in Europe and has several activities promoting medical research and medical education of young European specialists in internal medicine. FDIME supports young internists to attend the European School of Internal Medicine, participate in the European Exchange program and also provide grants for research in Internal Medicine.

You are also invited to pose additional questions, which we can try to answer in one of our next newsletters.

1Can a person who was vaccinated still be contagious and spread the virus to others?

Vaccination with BioNTech or Moderna vaccine provides a 95% protection of symptomatic disease, as from 7 days after the second vaccination. It is not 100% protection. These 5 % do not know, that the vaccine did not stimulate protective antibodies and therefore they can be infected with SARS-CoV2 and spread it with or without symptoms. Also, some people among the 95% who get the protection from vaccine, might at least theoretically be able to develop mild, local infection of the mucous membranes that render them potential spreaders of the virus -although probably this would happen for a very limited time and to a lower extent. For these reasons, it is important that also vaccinated people keep on wearing facemasks and follow measures of social distancing.

2Normal infection path is via mucous membranes. The vaccine is injected in the muscle, the same as the ‘flu vaccine. Will it be less effective this way rather than orally, as the polio vaccine is given?

Compared to the seasonal ‘flu, which is also infecting via mucous membranes and the vaccine given in the muscle, it is expected to be efficient enough.

3How is the vaccination protection tested in the trials?

Two similar populations (sex, age, comorbidity, etc.) are compared after one group received the vaccine and the other did not. In the follow up the number who develop the disease in both groups are compared. Intramuscular administration is the only tested pathway at this moment.

4Is there any protection after the first injection of the vaccine? After how many days is there some protection? How great is the protection after the second injection (full vaccine)?

The infection curves for the cumulative incidence of COVID-19 in the trial separate at about 10 days. This supports the conclusion, that 10 days after the first injection immunity rises. In a small study population there was up to 80 % prevention of COVID-19 infection compared to the placebo group after 28 days.

Pfizer-BioNTech and Moderna

5Can persons who received the two vaccine injections, still get infected when exposed to the virus and spread the virus?
When the vaccine works, the virus will be rejected. In those, whom the vaccine did not stimulate immunity, infection may occur. This chance seems fairly low (≤ 5%). See also question 1.
6After vaccination, how does a patient find out that he is infected with the SARS-CoV2 virus?
When the persons have no symptoms, they do not find out. It is similar to the persons who are not vaccinated and infected. They may spread the virus without knowing, but chances are of course very low.
7How long is the person protected against any of the Covid-19 virus mutations after two injections? Has the vaccination to be renewed every year?
It is not known yet. Protection is for at least 6 months.
8So far it is not possible to vaccinate children, so they can spread the virus. How long will it last until children can be vaccinated?
BioNTech and Moderna are planning to test their vaccine in a pediatric population.
9Is there any drug on the market or in the pipeline for the treatment of the Covid-19 infection?
There are several non-specific drugs which are known to improve the course of the disease. Genetically produced fragments of regular antibodies against spike protein of the SARS-CoV2 virus, called nanobodies, neutralize very specific and efficient the S(spike)1-protein and therefore inhibit the entrance of the virus into the cell of the host. Nanobodies can be produced in microbial systems. This could be a therapeutic approach. Also, different monoclonal antibodies able to bind the coronavirus are currently being tested as a potential treatment for SARS-CoV2 infection. These drugs block the capability of the virus to enter the cells and make it more easily recognizable by the immune system. Likely, the monoclonal antibodies are effective only if administered very early in the infection.
10Are there any treatments available for the long-term treatment of the Covid-19 symptoms?
Not that we know of. There is still a lot to research - many countries are now collecting data and running studies on long-term effects of Covid.The studies require a longer follow up, e.g. two years.
11When do I have to repeat the vaccination when I have had the two injections?
It is not known for how long the memory cells respond. Moderna has measured and published on the serum-antibody response to their vaccine. It was only about 2-fold decline of antibodies after about 4 months. In influenza vaccine using the mRNA method the decline is about 6-fold. It remains uncertain.
12How is the protection of the various vaccine against the new mutations?
Moderna vaccine appears to work against more infectious variants of the Covid-19 virus. However, more data are required and also must be peer reviewed. This probably also holds true for the other vaccines.
13Are vaccines generally produced and then stored until required?
Yes. Only short term-storage at present.
14Why is there no multi-vaccine against SARS-CoV2, seasonal flu and others?
Too early to say, but this could be available in the future.
15In the future, will there be a vaccine, which is self-adapting when the virus mutates?
Not self-adapting but adaptations made by researchers is being done with the influenza vaccinations already in use now.
16Is the quality level of the various vaccine products guaranteed from production to the point where people are vaccinated?
Yes. Quality insurance is given by the producer. But the delivery implicates other actors at the national and local level. It is the responsibility of the national drug agency and of the professionals to ensure that high standards are maintained throughout this process.
17Can the vaccine against Covid-19 affect the effectiveness of other vaccines applied earlier or later?
Probably not, but only observational studies will confirm.
18Can SARS-CoV2 be transmitted by blood transfusion?
So far no cases are reported.
19Does the vaccine cause side-effects?

Reports from both vaccines show a higher rate1 of systemic adverse events within 7 days after the second dose compared to the first. Fever, fatigue, myalgias, chills, arthralgia were reported.


  1. 79.4 % systemic adverse events after second dose after mRNA-1273 SARS-CoV-2 Vaccine versus 36.5 % after placebo.
    (LR Baden DOI:10.1056/NEJMoa2035389)
20Do asymptomatic persons at the time of testing stay asymptomatic in the long-term?
Available data suggest that about ⅓ of PCR positive persons are asymptomatic at the time of testing. In the long-term ¾ of these persons will remain asymptomatic.

Questions answered by Verena Briner, with some help of other FDIME Board members.

The Foundation for the Development of Internal Medicine (FDIME),

Daniel Sereni, Ramon Pujol, Jan Willem Elte.

With the help of Imad Hatem, Nica Cappellini, Lorenzo Dagna, Chris Davidson, Runolfur Palsson, Stefan Lindgren, Vereny Briner, Werner Bauer (in random order).