  Since the Covid-19 pandemic is a global threat to health that few can fully
escape, it has given a unique opportunity to study international reactions to a
common problem. Such reactions can be partly obtained from public posts to
Twitter, allowing investigations of changes in interest over time. This study
analysed English-language Covid-19 tweets mentioning cures, treatments, or
vaccines from 1 January 2020 to 8 April 2021, seeking trends and international
differences. The results have methodological limitations but show a tendency
for countries with a lower human development index score to tweet more about
cures, although they were a minor topic for all countries. Vaccines were
discussed about as much as treatments until July 2020, when they generated more
interest because of developments in Russia. The November 2020 Pfizer-BioNTech
preliminary Phase 3 trials results generated an immediate and sustained sharp
increase, however, followed by a continuing roughly linear increase in interest
for vaccines until at least April 2021. Against this background, national
deviations from the average were triggered by country-specific news about
cures, treatments or vaccines. Nevertheless, interest in vaccines in all
countries increased in parallel to some extent, despite substantial
international differences in national regulatory approval and availability. The
results also highlight that unsubstantiated claims about alternative medicine
remedies gained traction in several countries, apparently posing a threat to
public health.
