As we all know, we are facing a fifth wave of infections in Spain with millions of people with the full vaccination schedule and many others waiting for the second dose.

Perhaps you have taken a PCR test with us and have tested positive with a very high viral load, even after having been vaccinated. With perplexity, you may have asked us if the results were correct and if there was an explanation.

And we will have told you that yes, there is.

Vaccination is the key to overcoming this pandemic, but lately we are seeing an alarming increase in infections and re-infections.

This can be explained by several factors:



Vaccines do not cover 100% of the contagion, neither of suffering or transmitting the disease. In general, these vaccines reduce the symptomatological picture associated with COVID, i.e., even if you are vaccinated, you can still contract the coronavirus and also transmit it, but you will generally pass the disease better.

Why is this important?

It is very likely that in the coming months we will see headlines about a higher percentage of vaccinated people being infected than unvaccinated people. We should not worry, this is simply because the number of vaccinated people will increase as time goes by (Jiménez and Ortega-Prieto, 2021).

However, thanks to the vaccine, the number of people requiring hospitalization for severe COVID will be proportionally much lower.

Let us give an example: let us imagine that we have a group of 20 people at risk in which 17 have been vaccinated and 3 have not; and of the vaccinated 5 are infected and of the 3 non-vaccinated 2 are infected, all 5 with severe symptoms. We could then read a headline stating that 25% of hospitalized persons are vaccinated compared to 10% of unvaccinated persons, which, although true in absolute terms, gives rise to a possible error of interpretation.

The reality hidden by these data is that approximately 30% of those vaccinated require hospitalization compared to 66% of those not vaccinated. In other words, although the vaccine is not infallible, it does reduce the percentage of people requiring hospitalization.


On the other hand, the Delta variant is proving to be much more contagious and aggressive than the others, producing much higher viral loads, much lower and longer-lasting CT (Cycle Thresholds) values and more severe symptoms.*

In Spain, in July 2021 for example, this variant accounted for 68% of the infections that have been genetically sequenced, but the figure could be higher (Ministry of Health of the Government of Spain, 2021). In countries such as the United Kingdom there is already talk of up to 90% of the latest cases of COVID (BBC News, 2021).

Recent studies, such as that of the CDC (Centers for Disease Control and Prevention, 2021), indicate that the Delta variant could have approximately the same transmission capacity in unvaccinated people as in vaccinated people and that the vaccines currently on the market are less effective in the case of this variant. 

In addition, it also indicates that infections in vaccinated people may occur more in environments with a high level of congregation and in those risk groups in which the vaccine from the beginning may give more failures, such as the immunocompromised or the elderly, among others.

From Life Length we recommend maintaining all anti-COVID measures proposed by the Ministry of Health and perform COVID screening tests if you have the slightest doubt about a possible infection.

If you need a test, you can book an appointment to do it in our facilities in Paseo del General Martínez Campos, 46, Madrid from Monday to Sunday.

If you take care of yourself, you take care of us all.

*NOTE: The lower the CTs, the higher the viral load.


Reference articles:

  1. Jiménez, J.M. y Ortega-Prieto A.M. (2021).  ¿Cómo es posible que la mayoría de hospitalizados por covid-19 sean personas vacunadas? Periódico ABC.
  2.  Ministerio de Sanidad del Gobierno de España, (2021). Actualización de la situación epidemiológica de las variantes de SARS-CoV-2 de mayor impacto e interés en salud pública en España.
  3. BBC News, (2021). Variante delta: cuáles son los síntomas y el peligro de que se propague con tanta facilidad.
  4. CDC, USA Government, (2021). Improving communications around vaccine breakthrough and vaccine effectiveness.