The Impact of the Patras Carnival on the Course of the COVID-19 Pandemic and the Outbreak of Influenza A: A Multicenter Cross-Sectional Study

Background: We investigated the impact of the indoor mass gathering of young people during the Patras Carnival in Greece on the course of the COVID-19 pandemic and the influenza A epidemic. Materials and Methods: For influenza A, we tested 331 subjects with high fever (>38 °C), who arrived at five separate private laboratories over a two-week period after the carnival, via rapid test. One hundred and eighty-eight of them were young adults (17−35 years old), all unvaccinated against influenza A but all immunized against SARS-CoV-2, either through vaccination or previous infection. For the SARS-CoV-2 pandemic, we tested 2062 subjects at two time periods, two weeks before and two weeks after the carnival, also via rapid test. Additionally, we examined 42 samples positive for influenza A and 51 samples positive for SARS-CoV-2 for the possibility of co-infection via molecular testing (i.e., RT-PCR). Results: 177/331 (53.5%) subjects tested positive for influenza A, and 109/177 (61.6%) of the positive subjects were young adults, and 93/109 (85.3%) of these subjects were tested in the first week after the carnival. Additionally, 42 samples of those subjects were molecularly tested, and 5 were found negative for influenza A but positive for SARS-CoV-2. Regarding the SARS-CoV-2 pandemic, the increase in the positivity index for young adults between the pre-carnival and post-carnival periods was moderate. Conclusions: Our study indicates that the indoor mass gathering of young people during the carnival contributed to the outbreak of an influenza A epidemic and had a moderate but not statistically significant impact on the course of the SARS-CoV-2 pandemic, corroborating the crucial role of vaccination against the epidemic’s waves. It also showed the need for the use of high-quality rapid tests for their management.

Regulation of retinal neurite growth by alterations in MAPK/ERK kinase (MEK) activity

Activation of the extracellular-signal regulated kinase (ERK) cascade may be involved in the promotion of neurite outgrowth by a variety of stimuli. For example, we have previously shown that laminin (LN) and N-cadherin activate ERK2 in chick retinal neurons, and that pharmacological inhibition of MAPK/ERK kinase (MEK), the major upstream ERK2 activator, severely impairs neurite growth induced by these proteins. We have therefore hypothesized that ERK activation through MEK is required for optimal induction of neurite growth by these proteins. Here we show that expression of mutant MEK in transfected retinal neurons alters neuronal responses to LN in a manner consistent with this hypothesis. Neurons expressing a constitutively active MEK construct extended longer neurites on LN than controls, while neurons transfected with a dominant negative construct extended shorter neurites. Further, experiments in which transfected neurons were replated onto polylysine substrates suggest that activation of MEK is sufficient for neurite promotion on a non-inducing substrate, and neurons replated onto LN confirm the pharmacological data that inhibition of MEK activation inhibits LN-induced neurite growth. We conclude that ERK activation plays a direct role in the promotion of neurite outgrowth from retinal neurons by LN.