Background:

Home confinement policies during the COVID-19 pandemic limited sun exposure and may have influenced on vitamin D levels.

Objective:

To assess changes in 25(OH)D during the COVID-19 pandemic and the impact of Mandatory Preventive Social Isolation (MPSI) on UV radiation recommended dose modified by clouds for the synthesis of vitamin D (UVDVC).

Material and methods:

A retrospective study was carried out on 15,908 patients in whom the level of 25(OH)D was determined between January 2019 and December 2021 in a centralized laboratory in Rosario, Argentina.

Results:

Lower levels of 25(OH)D were documented in people younger than 40 years during 2020, as well as a variation during the pandemic period, with lower values in the first wave. Lower levels of 25(OH)D were recorded in the post-MPSI period in comparison with the MPSI period (p < 0.00001), in addition to a higher frequency of hypovitaminosis D (48.6% vs. 36.1%). These differences were not observed in the comparison of the same periods of 2019. UVDVC did not vary between 2019 and 2020.

Conclusions:

The restrictions due to the COVID-19 pandemic led to a higher frequency of hypovitaminosis D and lower frequency of optimal values.