Background The COVID-19 pandemic and subsequent restrictions increased the psychological distress of the population while the use of on-site mental health care decreased. The provision of online mental health care was therefore scaled up in many European countries. The extent to which online care can deliver services to all people (horizontal equity) according to their needs (vertical equity) is unknown. This study assessed whether online advice-seeking was related to mental health needs and whether different population subgroups were equally likely to seek advice. 

Methods A longitudinal, online survey was carried out in Belgium in April, June, and November 2020. 13,150 different individuals participated in at least one study wave. At the end of each wave, information on how to receive help was provided. Psychological distress was measured using the GHQ-12. We used logistic regression to compare the association between psychological distress and online advice-seeking across waves and sociodemographic groups. 

Results 29% of the respondents sought online advice in April, and one fifth in June and November. The frequency of advice-seeking was associated with higher psychological distress (OR = 1.24, 95% CI:1.22–1.26). Women, young people, respondents with higher education, and respondents with less social support were more likely to seek advice online. 

Conclusions Online mental health advice seems to achieve vertical equity. Sociodemographic variables were, however, better predictors of psychological distress than advice-seeking. More attention should be paid to older and less well educated men, who were less likely to seek advice. In the longer term, the responsiveness of online services needs to be assessed.