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Posts Taged viral-load

Prof. Pilar Marco, in the program “Meridiano Turing” of RTVE explains the COVID-19 tests.

The last edition of the program “Meridiano Turing” of RTVE interviews Maria Pilar Marco Head of CIBER-BBN and IQAC-CSIC group Nb4D and NANBIOSIS-ICTS Unit 2 Custom Antibody Service (CAbS), Cesar Fernández (Head of the Chemical Transducers Group at IMB-CNM, CSIC) and María Cruz Minguillón (EGAR group at IDAEA)

Pilar Marco y César Fernández, the authors of the block of the CSIC’s report entitled “Containment and diagnosis“, explain wich is the best way to diagnose COVID and how reliable are the tests in this moment.

What is needed is to detect an infection -says Pilar Marco- is viral material and we have two types of tests to detect viral material:
– Those that detect the viral RMA, which is the genetic material of the virus. These test known as “PCR”, were the first to be used and are quite reliable PCR is a technology that expands the genetic material, making many copies what makes it possible to detect the viral material with very low viral load
– And during the month of September have became famous what are known as the “antigen tests” (they also came out at the beginning, but they were of low quality). These tests do not detect the genetic material but the structural proteins of the virus.

Serological tests should not be used to diagnose an infection because they do not detect the virus, what they detect is the reaction that the host has in the presence of an infection, that is, the antibodies that our body produces to defend itself against the infection and this occurs from the first moment but is not detectable until practically seven days after being infected. Therefore serological tests have limited utility to diagnose the infection, they serve to monitor the evolution and immunological status of the patient, if he is producing antibodies against the virus and how it evolves The virus remains elevated for months, but it does not mean that if you have had the disease and the rsults fo serological tests are negative, you are not prepared to face the virus, since we have memory cells that will surely produce antibodies again.

Cesar Fernández explains that the sample is the same in PCR and antigen tests, but the time it takes to obtain an answer is different. Both type of tests are recommended depending on the situation and the environment in which they are used, PCR tests have been used more massively and are more reliable in the sense that they let out much fewer positives, the number of false negatives they provide is very low, but they are also more expensive tests and need more time from the moment the sample is taken until the result is obtained (minimum 24 hours) since they are carried out in clinical analysis laboratories. The antigen tests can be carried out in 15-30 minutes in the place where the sample is taken and their cost is very low compared to that of the PCR, which is why they are very useful for screening studies of the levels infection that may exist in a community. Currently, work is being done on carrying out the antigen tests in saliva, this would facilitate the taking of samples and would not generate practically social rejection. Studies are also being done on the use of nasal smears in which the sample is taken at the beginning of the nasal cavity, resulting in much less annoying. Antigen tests due to their low cost and ease use open the possibility of performing in a very repetitive way.

Regarding the measurement of viral load, it is given by the PCR, while in the antigen tests the detection is visual, a colored line appears, similar to the pregnancy tests, with greater or lesser intensity, with which the information they give on viral load is semi-quantitative, that is, the interpretation is quite subjective.
The viral load of the disease appears a few days before sinthoms are shown (the peak is two days before) and can be spread to other people. This also occurs with asymptomatic infected people, with the only difference that, after this peak, the viral load falls very quickly and the disease does not appear.

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NANBIOSIS scientists in Aragón, explain on TV their research againts coronavirus

The special program on the coronavirus pandemic  by “En Ruta con la Ciencia” of Aragón Televisión, analyzes different aspects of the disease with special attention to the work of Aragonese scientists. Among them, two  research groups that coordinate NANBIOSIS units 9 and 27.

Starting at minute 44’45 ‘of the program, Doctor Jesús Lázaro, researcher of the BSICoS group of I3A-UZ and CIBER-BBN, led by Pablo Laguna, which coordinates NANBIOSIS U27 High Performance Computing Unit, explains his research. For almost 3 years, Jesús Lázaro had been working on a European project to develop a respiratory and heart rate monitoring system for patients with EPOC to control and predict episodes of worsening disease, but the current situation has led him to redirect his goal to try to provide solutions in this crisis and have creates an application for the mobile phone to detect from our home, if we have a viral infection: – “The parameters measured by this application have to do with the nervous system Autonomous, – explains Jesús Lázaro – they are the heart rate, its variability and the respiratory rate, these three parameters would allow observing a response through SARS-COV-2. The application works based on a technology that uses the flash of the mobile phone camera as a receiver to obtain a signal that is proportional to the blood volume of the finger put on the flash light, what allows detecting both, the number of beats per minute and the morphology of the arterial pulse, to obtain the respiratory rate. At the moment this application has been tested by the research staff and the next phase is to assess it with the general public. As the application is based on detecting autonomic markers, a very high sensitivity is expected, as well as a very low specificity, which would allow detecting not only SARS-COV-2 but analyzing these parameters in other contexts and in other diseases, even detecting other eventual viruses of other eventual pandemics ”.

Further information on the research project here

Starting at 28’14 ’’ One of the problems of the coronavirus test is what is known as false negatives, people who have passed the disease, but are not detected and could continue to spread it. A research group is developing early diagnostic tests to try to reduce this error rate. Pilar Martín Duque, at the IACS Aragonese Institute of Health Sciences, is a researcher of the NFP group of the INA and the CIBER-BBN, led by Jesús Santamaría, which coordinates NANBIOSIS U9 Synthesis of Nanoparticles Unit : – “All techniques have a detection limit and a sensitivity, it is necessary to have a minimum amount of virus in the body for the virus being detected, if the viral load is low it may not be detected at that time, it is possible that some patients with a low viral load recover, but in other cases the virus begins to grow and after two weeks they can be positives”- explains Pilar Martín. Her project makes PCRs more effective by concentrating the viral load before testing. – “There is a curious case, – continues Pilar -, of an American navy ship, moored in China, in which five sailors were detected to be infected by coronavirus, so they were quarantined during fourteen days and, after new tests with negative results, they were allowed to return to the United States on the ship. However halfway through the journey, the same five sailors suffered an outbreak of the disease. Therefore, our study would be useful for detecting patients with the virus tested for the first time or for not discharging patients who had been already diagnosed if they really are not yet negative”.  It is estimated that 10% of the population has infected 80%, these 10% are the so-called “superspreaders”, they are infected with a high viral load, but they feel well and do not know about it. For example, there have been several cases in choirs, such as the Choir of Zarzuela in Madrid, where 53 members were contagious out of the 80 members form the choir, this is because when singing or speaking very loudly, more drops are produced that carry the virus”. But why do some people become infected before others? Pilar explains that this is related to some, already known, receptors for entry of viruses, the AC2 receptors, and there are people who has more of these receptors than others.

Further information on the research here:

If we have learned anything from this pandemic it is the importance of health and research, a robust research system has the knowledge, tools, and human talent to respond to any situation. If we want to be prepared for the next pandemic, it is important and essential to continue betting on research.

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