Reply to Ialongo et al. Vitamin D, SARS-CoV-2 and Causal Associations in Transversal Studies: The Time-Series Analysis to Reveal Potential Confounders. Comment on "Gaudio et al. Vitamin D Levels Are Reduced at the Time of Hospital Admission in Sicilian SARS-CoV-2-Positive Patients. Int. J. Environ. Res. Public Health 2021, 18, 3491".

We read the comment by Ialongo et al. [...].

Vitamin D Levels Are Reduced at the Time of Hospital Admission in Sicilian SARS-CoV-2-Positive Patients.

The coronavirus disease 2019 (COVID-19) pandemic poses a worldwide healthcare challenge that needs an efficient response. Unfortunately, to date there is no highly effective treatment, so a deep understanding of COVID-19 risk factors could be an important step in treating the disease. Vitamin D affects the immune system in many different ways, and other authors already found that COVID-19 patients have low levels of vitamin D. In our retrospective study, we evaluated the vitamin D status at the time of hospital admission in 50 COVID-19 patients in Sicily, which is the southernmost region of Italy, and compared them with 100 control subjects matched for age and sex. Our data showed markedly low levels of vitamin D in patients with a positive polymerase chain reaction (PCR) for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), but no association was found with inflammation markers or clinical severity. Vitamin D levels were reduced at the time of hospital admission in Sicilian SARS-CoV-2-positive patients, but it is not clear whether this condition has an impact on the clinical course of COVID-19.

A strange case of dyspnoea.

Acquired neuralgic amyotrophy, described for the first time by Parsonage and Turner, is a rare idiopathic disease that may occur in otherwise normal healthy individuals. It typically begins with sudden, unilateral shoulder pain that may also involve the neck and/or arm. Less frequently, the disease involves nerves other than those of the brachial plexus, such as phrenic nerves, resulting in dyspnoea. The diagnosis is based on the clinical presentation and is generally supported by electroneurography/electromyography. We report the case of a 45-year-old white man who was referred to our clinic for acute dyspnoea preceded by severe neck and right shoulder pain. Corticosteroid therapy ameliorated the clinical picture, but without a complete recovery.