Evolution of antibodies against SARS-CoV-2 over seven months: experience of the Nationwide Seroprevalence ENE-COVID Study in Spain

ObjectivesTo analyse temporal trends in SARS-CoV-2 anti-nucleocapsid IgG throughout the four rounds of the nationwide seroepidemiologic study ENE-COVID (April-November 2020), and to compare the fourth-round results of two immunoassays detecting antibodies against nucleocapsid and to S protein receptor-binding domain (RBD). MethodsA chemiluminescent microparticle immunoassay (CMIA) was offered to all participants in the first three rounds (Abbott; anti-nucleocapsid IgG). In the fourth round we offered this test and a chemiluminescence immunoassay (CLIA) (Beckman; anti-RBD IgG) to i) a randomly selected sub-cohort, ii) participants who were IgG-positive in any of the three first rounds; and iii) participants who were IgG-positive in the fourth round by point-of-care immunochromatography. ResultsImmunoassays involving 10,153 participants (82.2% of people invited to donate samples) were performed in the fourth round. A total of 2595 participants (35.1% of participants with immunoassay results in the four rounds) were positive for anti-nucleocapsid IgG in at least one round. Anti-nucleocapsid IgG became undetectable in 43.3% of participants with positive first-round results. Pneumonia was more frequent in participants with anti-nucleocapsid IgG in all four rounds (11.2%) than those in which IgG became undetectable (2.4%). In fourth round, anti-nucleocapsid and anti-RBD IgG were detected in 5.5% and 5.4% participants of the randomly selected sub-cohort, and in 26.6% and 25.9% participants with at least one previous positive result, respectively. Agreement between techniques was 90.3% (kappa: 0.72). ConclusionsThe response of IgG to SARS-CoV-2 is heterogeneous and conditioned by infection severity. A substantial proportion of the SARS-CoV-2 infected population may have negative serologic results in the post-infection months.

[Biodefense: a new challenge for microbiology and public health]. / Biodefensa: un nuevo desafío para la microbiología y la salud pública.

Bioterrorism and the potential use of biological weapons has become an important concern of governments and responsible authorities. An example of this threat occurred in 2001 in the USA, when letters were sent containing spores of the agent that produces anthrax; this resulted in some deaths, and caused panic and negative effects on the world economy. If this small-scale event was able to cause such a huge impact, the repercussions of a massive attack could be catastrophic. In many countries, these events have resulted in the implementation of measures directed toward preventing and responding to bioterrorist threats and acts. As a whole, these measures are known as biodefense. This article briefly analyzes several aspects related to detecting and identifying acts of bioterrorism, and considers the biological agents that are implicated. The microbiological diagnosis that allows identification of the causal agent, a key point for taking suitable control measures, is also included.

Biodefensa: un nuevo desafío para la microbiología y la salud pública / Biodefense: a new challenge for microbiology and public health

El bioterrorismo y el uso potencial de armas biológicas se ha convertido en una preocupación importante de los gobiernos y autoridades competentes. Como ejemplo, el envío de cartas con esporas del agente causante del carbunco en Estados Unidos en 2001 ocasionó varias muertes, causó pánico y tuvo repercusiones negativas en la economía mundial. Si este incidente, a pequeña escala, produjo semejante impacto, los efectos de un ataque masivo podrían ser catastróficos. En muchos países éste fue el punto que marcó el inicio de la toma de medidas encaminadas a prevenir y responder ante amenazas y actos bioterroristas, acciones que, en su conjunto, se conocen como biodefensa. Este artículo pretende analizar someramente algunos aspectos relacionados con la detección e identificación de este tipo de acciones y los agentes biológicos implicados. Se considera el diagnóstico microbiológico que permite la identificación del agente causal, punto clave para la toma de medidas de control adecuadas (AU)

Bioterrorism and the potential use of biological weapons has become an important concern of governments and responsible authorities. An example of this threat occurred in 2001 in the USA, when letters were sent containing spores of the agent that produces anthrax; this resulted in some deaths, and caused panic and negative effects on the world economy. If this small-scale event was able to cause such a huge impact, the repercussions of a massive attack could be catastrophic. In many countries, these events have resulted in the implementation of measures directed toward preventing and responding to bioterrorist threats and acts. As a whole, these measures are known as biodefense. This article briefly analyzes several aspects related to detecting and identifying acts of bioterrorism, and considers the biological agents that are implicated. The microbiological diagnosis that allows identification of the causal agent, a key point for taking suitable control measures, is also included (AU)