Pfizer's coronavirus vaccine: Everything you need to know

As the first shipment of Pfizer coronavirus vaccines has already landed in Israel, the vaccination campaign against COVID-19 is expected to begin very soon here.

The first to be vaccinated in Israel will be the healthcare workers and people who are at the highest risk of suffering from complications of the disease.

This vaccine raised quite a few concerns regarding its safety, its application and its consequences on our lives, as it is the first ever vaccine against coronavirus to be marketed in the West, and we don't know about its long-term effects.

Clalit health fund provided a question/answer form to explain everything that is important to know about it.

What kind of vaccine is it? How effective is it? What side effects can it cause? Is it dangerous? And how was it developed so fast?

Dr. Batsheva Gottesman, a senior physician at the Meir Medical Center's Infectious Diseases department operated by the Clalit Group, is here to answer these questions. She also serves as a consultant to the Clalit Community in the field of infectious diseases and the use of antibiotics.

What kind of vaccine is being developed against corona?

There are several technologies for creating vaccines, and each method has advantages and disadvantages.

Pfizer's coronavirus vaccine does not belong to the classic categories of live and killed vaccine, but to the messenger RNA (mRNA) technology.

This technology has been known in medicine for about a decade and is applied not only in the vaccine developed by Pfizer, but also to the one developed by Moderna.

How does Pfizer's vaccine work?

The spikes that characterize the coronavirus and give it the shape of a crown play an important role in the penetration of the coronavirus into human cells.

The vaccine only introduces into the body the spike protein found on the surface of the coronavirus, without exposing the vaccinated person to the whole virus. Once the immune system attacks the spikes, it actually neutralizes the virus.

What is special about the vaccine technology developed by Pfizer and Moderna is that it is asking our bodies to do something they do every day: protein synthesis, the process where cells make proteins.

Moderna and Pfizer are simply delivering a specific mRNA sequence to our cells. Once the mRNA is in the cell, human biology takes over. Ribosomes read the code and build the protein, and the cells express the protein in the body.

These operating instructions are carried by the mRNA. Once the mRNA completes its mission, it is destroyed and does not remain in the body. This method has a significant advantage – it does not use a live virus, so there is no risk that following the vaccine, the virus will begin to spread in the body of the vaccinated person.

Is Pfizer's vaccine effective?

Pfizer's coronavirus vaccine has been tested in several countries and in several stages, as is customary in any vaccine development process.

In the first phase, the vaccine was tested on monkeys, and it turned out to be effective. The vaccine was later tested in humans, and it became clear that the response was a significant production of antibodies to the coronavirus.

In the last stage, it is tested [to determine whether] the vaccine effectively prevents disease in the general population and not only among relatively few experimenters. At this stage, more than 40,000 volunteers were vaccinated who were divided into two groups: one group received the real vaccine, while the other group received a placebo vaccine – a sham vaccine that does not contain the active ingredient.

At the end of the third trial phase, Pfizer announced that the efficacy of the vaccine it had developed was 95%. For comparison: the effectiveness of the flu vaccine ranges from 50% to 70%, varying from one year to the other.

Is the vaccine effective even when it comes to older vaccinators and those who suffer from various background diseases?

Yes. The study included both adults and those suffering from background diseases. These are people who are at increased risk of suffering from a serious illness following infection with corona. These are the people who are most important in preventing their infection with the corona, and for whom the vaccine has also shown high efficacy.

What are the side effects of the vaccine? Is the vaccine safe?

Monitoring of side effects is a key part of any development of a new vaccine, and they are ranked in three degrees of severity: mild, moderate and severe. This monitoring is the responsibility of an independent, external company and not the manufacturing company, to ensure accurate data without bias.

These are the side effects observed during follow-up lasting about two months: fever, fatigue and headaches. Those receiving vaccines have also reported pain and swelling at the injection site. However, these side effects were mostly mild and passed within a few days.

Of the approximately 20,000 volunteers who were vaccinated with Pfizer's true vaccine, only three volunteers developed "serious" side effects: shoulder injury, arrhythmia or lymph node enlargement. Six of the participants in the experiment died during the trial: two of them received the vaccine and the other four received a placebo. The committee that examined these deaths determined that none of them were related to the vaccine.

As for the long-term side effects: There is, of course, no information about that, as it has just been developed.

However, from many years of experience gained from other vaccines that have been developed, we know that the side effects following receiving vaccines occur in the first few weeks after vaccination and we already have a few weeks' experience.

Who should not be vaccinated?

• The vaccine should not be given to anyone who has a history of severe allergic reaction to any vaccine, drug or food and who therefore carries an epinephrine syringe with him.

• Those under the age of 16, as the information about them is limited at this stage.

Although the existing data do not indicate a concern that the vaccine harms pregnant and lactating women (or fetuses or breastfed infants), until further data are available, it is not recommended to give the vaccine during pregnancy and lactation.

The recommendation at this stage is to postpone receiving the vaccine until after the end of the pregnancy and breastfeeding, for reasons of extreme caution, as is customary with any new vaccine or medical preparation. Pregnant and lactating women are always the last to be approved for new vaccines.

What about patients with a weakened immune system?

Because the new vaccine for corona is not based on a "live" virus, there is no danger that it will multiply in the body, so the vaccine can also be given to those who suffer from a weakened immune system.

As is well known, those who suffer from a weakened immune system are at high risk for serious illness and death if they become infected with the coronavirus, so it is advisable to vaccinate them.

Keep in mind, however, that the immune system of these people may not be able to produce antibodies to the desired extent, and the effectiveness of the vaccine in such a case may be less.

How is it that the vaccine got to the distribution stage so fast? Didn't they make "shortcuts"?

Keep in mind that mRNA technology already existed (it was developed, among other things, to deal with diseases caused by other corona viruses such as SARS and MERS). The development of this technology has only accelerated in the wake of the current epidemic.

All the necessary steps in the development of the vaccine were done as required – and due to the high incidence of the disease, there was no need to wait for years until results were obtained.

This is in contrast to testing the effect of a vaccine for diseases that rarely occur. In such a case, a much larger number of participants is needed, as well as a longer follow-up, until patients with the disease under investigation are identified. As mentioned, since the prevalence of corona was high, it was possible to get results quickly.

How many vaccine injections should be done to get the best protection?

Two vaccine injections should be given 21 days apart.

I got vaccinated - for how long am I protected from the virus?

There is no answer to this question yet. Those who have contracted the coronavirus and recovered from it are protected for at least a few months (there were so far very few re-infections compared to the tens of millions who have already contracted the disease worldwide), but this cannot be claimed with certainty regarding the vaccine.

Prolonged follow-up will answer the question of whether in the future it will be necessary to get vaccinated again and again, similar to many other vaccines.

Can I get the coronavirus because of the vaccine?

Absolutely not, since it is not a live vaccine, but a single protein component of the virus that is unable to multiply and make the receiver of the vaccine contract the disease.

Before receiving the vaccine, is it worth doing a serological test (a blood test to find those who have already had Corona)?

There is no such recommendation, nor is there a need for it. It turned out that a small proportion of the experimenters in Pfizer's study received the vaccine after previously suffering from corona and recovering. No abnormal side effects were observed in them that were not observed in subjects who were vaccinated without having previously been in Corona.

I have been infected with corona in the past and have recovered – do I need to get vaccinated?

The vaccine will not be offered to those who are known for sure that they have contracted Corona and recovered - they are certainly not a high priority.