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Covid and antibodies: the secrets of immunity explained by an expert


Biochemist Jorge Quarleri and how vaccines contribute to immunity. It also talks about the difference that exists with the protection acquired by convalescents.

Paula galinsky

05/09/2021 17:12

  • Clarí

  • Society

Updated 05/09/2021 5:12 PM

Antibodies against coronavirus, natural and artificial immunity, quantity and quality.

Is the


of vaccinated and convalescent the same?

Is it worth taking a test to measure the protection left after the disease or vaccination?

How much time must be given to the body to generate it?

Jorge Quarleri

, biochemist and principal investigator of Conicet, answers the main doubts on this subject that in the middle of the second wave is on everyone's lips.

Can antibodies be measured in quantity?

What about quality?

Each factory or laboratory uses a different cutoff value.

Exceeding this value implies the detection of antibodies.

The result can vary greatly between people, it is impossible to generalize.

Quantity does not necessarily imply quality.

Quality antibodies are those that have

a neutralizing effect

and do not allow the virus to come into contact with cell receptors.

In other words, they do not let him put the key in the lock of the cell and thus infect it.

Is it possible to test if we have neutralizing antibodies?

It can and is done in the laboratory for research purposes, although it is not something that is being done in a particular way.

Why do some people make more antibodies than others?

The reason is not clear.

The only thing we do know is that in some immunosuppressed people the immune response against Covid 19 is almost nil.

The vaccine is also indicated for this group because it is considered risky and because in many other cases it does help to produce certain levels of immunity.

What is the best time to check the amount of antibodies?

It can only be consulted after three or four weeks of the first dose and 30 days after the second dose.

In many cases, after the first dose, people take the antibody test and are surprised by the absence of detectable immunity.


does not mean that they do not have antibodies


Questions and Answers about vaccines

Who can get vaccinated and who can't?

In principle, all people over 18 years of age could be vaccinated.

But the Ministry of Health of the Nation does not recommend its application to those who have a serious acute disease (infectious and non-infectious), chronic diseases that involve compromise of the general state, or important immunosuppressive treatments.

It is also discouraged due to a history of severe allergic reactions or "anaphylaxis" (with respiratory compromise requiring medical assistance) or serious complications after the first dose of any Covid vaccine.

Will the children be vaccinated?

Children will surely be vaccinated, but not now.

They are not a priority group because they are less contagious and complications are rare.

In addition, clinical trials are needed to study the safety and efficacy of vaccines in children.

In fact, Pfizer and Moderna are conducting clinical studies in adolescents.

Will we have to be vaccinated every year against the coronavirus?

Whether the Covid vaccine will be annual or not will depend on several factors.

Among them, the duration of the antibodies - it is not known until today how long they last - and if the mutations that occur are of such magnitude that they determine a "new strain", as occurs with influenza, which requires a vaccine per year.

Are vaccines safe?

The administration of any vaccine is a very safe process.

In some cases, vaccines can cause injection site reaction (redness, itching, pain, tenderness, swelling) and, to a lesser extent, fever, headache, tiredness, chills, loss of appetite, muscle pain, pain in the joints or sweating.

These reactions usually disappear in a few days and are mostly mild.

These signs are normal and mean that the body is generating an immune response.

In very few cases a mild (skin rash) or more severe (swelling of the face or lips or shortness of breath) allergic reaction may occur.

What adverse effects can they give?

With the Sputnik V vaccine, two cases of thrombocytopenia were detected in Argentina - a decrease in platelets, apparently due to an autoimmune mechanism.

It is a very low figure compared to the total doses given.

Thrombosis cases were reported worldwide with the AstraZeneca vaccine, especially in young women taking birth control pills.

With the Janssen vaccine, some cases of thrombosis were also reported in the United States.

But the European health agency recommended applying both vaccines because their benefits outweigh these potential risks.

With the Pfizer and Moderna vaccines, “anaphylaxis” type allergic conditions were observed, more frequent in previous severe allergies.

What kinds of adverse effects should be reported?

Generalized and severe allergic reactions, convulsive syndrome and fever over 40 °.

What do the efficacy and effectiveness of a vaccine mean?

The percentage of effectiveness of a vaccine is the protection provided by the vaccine under real conditions of use in common circumstances in the community and not specifically in a controlled study, which shows the efficacy.

The efficacy with the first dose varies according to the vaccines (see the data in the file for each vaccine).

With regard to effectiveness studies, the most important are those of Pfizer because they reflect what happens in real life: in Israel, between 14 to 21 days after the first dose, mortality decreased by 72 to 84% and cases bass decreased by about 80%.

What percentage of the population has to be vaccinated to achieve herd immunity?

To achieve herd immunity - the indirect protection against an infectious disease that occurs when a population is immune, as a result of vaccination or due to the immunity developed through a previous infection - the efficacy of vaccines must be taken into account and its coverage, in the sense of how many people agree to be vaccinated. If you are vaccinated with a highly effective formula and there is high coverage, people who remain unvaccinated have no one to get it from, because the virus is practically eliminated from circulation. If vaccinated with a formula that is 70% effective, but 100% of the population, herd immunity is achieved more quickly than with a 90% effective vaccine but 70% vaccination coverage. Virologist Anthony Fauci, chief medical consultant to the president of the United States,marks that the percentage of vaccinated necessary for herd immunity would be between 80% and 85% of the population of a country.

Are messenger RNA vaccines better than other developments?

It is a difficult answer even for the World Health Organization.

The countries that made the most progress with vaccination did so with messenger RNA vaccines.

With those of Pfizer, those countries are Israel, the United States and England (which also uses vaccines from AstraZeneca).

But Chile, which used inactivated vaccines such as the Chinese Sinovac, managed to reduce the transition to intensive care for those over 70 years of age with the two doses and a vaccination percentage in that group of over 80%.

That is, if you are vaccinated intensely, with two doses, the impact is likely to be very favorable with inactivated vaccines.

Going to the most categorical data, messenger RNA vaccines, with a single dose, already show a positive impact to reduce the disease at various ages.

Can the vaccinated and can they be infected?

If you are vaccinated, you could get sick if exposure to the virus was before your immune system has generated the protective response at the proper levels.

Most of the vaccines demonstrated an efficacy greater than 70%, this means that some people who receive the vaccine will not generate an adequate immune response capable of preventing the disease, although high efficacy has been demonstrated in preventing serious forms of Covid-19 .

There is still no accurate data to confirm that vaccinated people are not contagious.

Can someone vaccinated develop serious symptoms and even die?

Those vaccinated can be infected and, eventually, could develop serious symptoms, especially if they have diseases with immunodeficiencies or are carrying out immunosuppressive treatments.

These people may have a lower antibody response with a chance of making the disease more serious.

Older adults may have a phenomenon called “immunosenecence,” which is the lowest antibody response to a vaccine.

Do all vaccines protect for each strain or variant?

The new variants, especially the South African and Manaus variants, share a genomic mutation known as E484K that allows it to evade the immune system.

For this reason, the effectiveness of vaccines can be diminished or even very ineffective, as was the case with the AstraZeneca vaccine in South Africa.

With that of Manaus (which was detected here) there are few data on efficacy.

A recent study with researchers from Argentina and the United States showed that the Sputnik V vaccine could decrease its efficacy against these strains.

Some authors speculate that a third dose may be necessary or eventually adapt the vaccines to be more effective against these variants.

Can doses of vaccines be “mixed”?

A recent study in the UK looked at vaccinates who received a first dose with one vaccine and completed the second dose with another.

It is possible that vaccines may be exchanged in the future, but at the moment there are no definitive studies.

Therefore, the schedule must be completed with the same vaccine that was started.

Should the vaccines be reinforced with a third dose?

Not for now.

But it is not ruled out in the scientific community.

It will depend on the vaccine and its effectiveness.

If I am pregnant or breastfeeding, can I get vaccinated?

Pregnant or lactating people who have a high risk of exposure to SARS-CoV-2 infection and that cannot be avoided (health personnel, strategic personnel, teaching and non-teaching staff) or who have underlying diseases can be vaccinated. to include them within risk groups.

This recommendation is valid for all vaccines currently available in Argentina and does not apply to live and attenuated virus vaccines.

Breastfeeding has not been seen to transmit the virus, so if you are breastfeeding you can also get vaccinated.

How long do I have to wait to get the flu or pneumonia vaccine if I received or am about to receive the Covid vaccine?

It is recommended to separate the Covid vaccination 14 days from the application of another vaccine.

The flu and pneumococcal vaccine can both be received on the same day.

Can I get vaccinated if I have symptoms or am in close contact?

No. Vaccination should be postponed until recovery from acute illness (in symptomatic individuals) and until epidemiological clinical criteria for discontinuation of isolation have been met.

If I am under 60, what pathologies do I have to have to be in the priority group?

The risk comorbidities against Covid are diabetes, morbid obesity, cardiovascular, pulmonary or depressant diseases of the immune system.

When am I going to get vaccinated?

Given the shortage of doses, vaccination is being done in a phased manner and by priority groups.

And since each jurisdiction organizes it, these groups do not always coincide throughout the country.

The time to get vaccinated will depend on what priority group you are in, where you live and fundamentally on whether there are vaccines.

I had a turn and I couldn't go get vaccinated.

That I have to do?

With DNI, go to the same vaccination center where you had previously been assigned the shift.

I do not have an updated ID.

Can I still get vaccinated?

In Province, if you take your turn through the app you have to have the procedure number, which appears on the new ID card.

If you or the person for whom you are taking the turn (for example, an older adult) do not have it updated, you can do the management through the website.

In the City, management is also done through the website.

If I had Covid, how long do I have to wait to get the vaccine?

If you had Covid, you have at least a three-month period of immunity, therefore, the vaccine should not necessarily be applied at the time of clinical or epidemiological discharge.

In general, the consensus is to apply it within 90 days.

Those who received plasma or equine serum must wait 90 days before being vaccinated.

Why are there one-dose and two-dose vaccines?

Most of the Covid-19 vaccines available in Argentina and in the world so far require two doses, except for Janssen and Cansino, which are only one.

Depending on the type of vaccine, a second booster dose is required.

Another advantage of single-dose vaccines is logistics, being able to immunize more people at one time.

But the effectiveness of the single dose may be lower.

To find out, depending on the vaccine, we will have to wait.

What happens if I get the second dose after the recommended time?

This question also does not have a definitive answer.

There are vaccines that show some degree of protection from the first dose.

The clearest studies in this regard are those carried out in Israel, with the Pfizer vaccine, and in Great Britain, with the AstraZeneca vaccine - which as time passes, with a single dose, shows that immunity increases. .

It is not clear how long immunity lasts with a single dose and it is not known whether immunity is complete with a single application.

In the two-dose schedule, it is always advisable to complete the vaccination.

What happens if I miss the second dose?

Is protection declining?

Complete protection from two-dose vaccines is only guaranteed if that second dose is received.

Do I have to keep wearing a chinstrap if I got vaccinated?

According to the Centers for Disease Control and Prevention (CDC) of the United States, even two weeks after receiving any vaccine, people should take precautions in closed public environments, such as wearing a mask that fits well to the face.

In Argentina, the official recommendation extends the use of masks beyond this period, as well as other measures such as ventilation and social distancing.

Can the protection measures be relaxed if I am with another person already vaccinated?

If you are fully vaccinated and with another person also fully vaccinated, protection levels could be lowered, especially outdoors.

But if they are alone.

If there are more people, who are not known if they are properly vaccinated or if they belong to the risk group, we must continue with the protection measures, to protect the others.

How many vaccine contracts has Argentina closed so far?

The country closed five contracts: AstraZeneca, Sputnik V, Sinopharm, Covishield and with the Covax Fund.

Are some of the vaccines approved in Argentina manufactured in the country?

For now, only the active ingredient in the AstraZeneca vaccine is manufactured in Argentina, which is packaged in Mexico and the United States.

There are two other medium-term projects to manufacture the Sputnik V and Sinopharm vaccines in the country.

Is it possible to reach an agreement with Pfizer?

The government said it has resumed negotiations, but there have been no concrete announcements yet.

In order to move forward, in principle, they should modify the vaccine law.

Part of its content was an obstacle to be able to advance in the agreement at the end of 2020. Six Latin American countries have already signed their contracts with the American laboratory.

Why is the AstraZeneca vaccine so long to arrive?

So far, 60 million doses have been produced in Argentina, but bureaucratic problems and supplies for packaging delayed the second manufacturing phase.

There is no certain date on a possible arrival of lots.

What is the Sputnik light vaccine?

It is the same Sputnik V vaccine, but only component one.

This version was driven by the difficulty in manufacturing the second component.

The Russian Government has just authorized its use, and according to studies carried out in Russia, it protects 79.4% at 28 days after the administration.

The Russian authorities announced that they will export the Sputnik light to speed up vaccination in other countries.

What is the Covax Fund?

It is a global solidarity mechanism in which participating countries buy vaccines in order to access doses in the most equal way possible.

Argentina has so far closed a contract for 1.9 million doses until May, of the 9 million that would arrive in total.

How can the crisis in India influence the arrival of vaccines?

India is one of the countries that suffers the most from the pandemic and decided to close the export of vaccines to immunize its population.

At the same time, it is the main manufacturer of vaccines in the world, so that decision has a full impact on the export of vaccines and the greater difficulty of other countries in the world to access them.

What will the next vaccines be like?

There are currently 27 vaccines in phase 3, the most advanced stage of human trials, out of a total of 277 vaccines in development.

Of these, there are second and third generation vaccines, for example two formulas that are oral instead of injectable and seven that will be applied in a nasal spray.

If they are successful, they would not be available until the end of the year or the beginning of the next.

Is there a vaccine that is being investigated in Argentina?

One of these developments in the pre-clinical phase is a project by scientists from the University of San Martín and Conicet, which is being investigated at the Institute for Biotechnological Research (IIB).

It is a formula based on recombinant proteins and phase I studies in humans will begin in the coming months.

The vaccine could be available in a year and a half.


Eduardo López / head of the Medicine Department of the Ricardo Gutiérrez Children's Hospital and member of the expert committee that advises the national government

Romina Mauas / infectious disease physician advises Vittal and member of the Commission on HIV-AIDS and Sexually Transmitted Infections of the Argentine Society of Infectology.

The strategy of

vaccinating more people with the first dose

and delaying the application of the second is aimed at guaranteeing a primary response, which does not always translate into detectable antibodies but does translate into a low concentration that is also relevant and functional.

And, in addition, in the production of a certain immunological memory, which helps the body detect more quickly the entry of the virus and

generate antibodies in an accelerated way.

Do all vaccines generate the same kind of antibodies?

In the cases of vaccination with AstraZeneca and Sputnik V (also the case with Pfizer and Moderna), in which an immunogen is applied, the body receives the genetic information to make

protein S or Spike

, which is the spike that serves as the key. for the virus to enter the cell. In this way, the infection is simulated to teach the body how to react in case it really happens. In other words, it will show you the face of the virus

so that you can easily recognize it and act accordingly if necessary

. This stimulation of the protein S will produce antibodies that are directed only against that component. On the other hand, when vaccines such as


are applied

With the inactivated virus, different types of antibodies or immunoglobulins will be generated.

In other words, our immune system will be shown not only the face of the virus but also the color of the hair, the ears, the hands.

Are there differences with the antibodies generated by a convalescent patient?

Yes, there are

differences between artificial and natural immunity.

When the person is infected with Covid 19, the attacker is the complete virus, which forces the body to defend itself from all its parts.

And, unlike what happens with the inoculation of the virus or part of the inactivated virus, when the infection occurs, the offending agent multiplies, which generates an extra challenge in the body and, at the same time, another type of learning .

For this reason, the immune response that is triggered has particular characteristics.

For example, localized immunity is achieved in the mucosa through which the virus entered, something that does not happen with the same magnitude among vaccinated patients.

How long does it take for antibody levels to start to drop?

Existen cinco clases de inmunoglobulinas o anticuerpos. La de mayor relevancia, por ser la más duradera y más abundante en el plasma que circula en el organismo es la G (IgG). Las investigaciones con las que contamos hasta ahora indican que la IgG perdura en el cuerpo por lo menos por ocho meses.

También sabemos que cada 21 días disminuye a la mitad. La segunda dosis de la vacuna -o la primera en pacientes que ya tienen niveles elevados de anticuerpos por haber transitado la enfermedad- funciona como booster o refuerzo para afianzar la inmunidad y prolongar su presencia o retrasar su desaparición.

La memoria inmunológica es otro de los elementos relevantes sobre el que tampoco hay certezas de duración, aunque todo indica que podría extenderse por mucho tiempo. Solo a modo de ejemplo se puede tomar lo que ocurre con la vacuna antitetánica que guarda memoria inmunológica por hasta 50 años.

Las personas con anticuerpos, ¿pueden reinfectarse o contagiarse por primera vez después de la vacuna y transmitir el virus?

Los anticuerpos no implican inmunidad absoluta. Pero sí suelen derivar en cuadros leves en caso de reinfección o de contagio después de aplicada la vacuna. Si se contagian pueden transmitir el virus por lo que es importante que se sigan cuidando, no solo por ellos, si no también para proteger al resto de la población.


Mirá también

Vacunados, recuperados y “vírgenes”: diez preguntas sobre los contagios de Covid en la segunda ola

Source: clarin

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