We examined how age and exposure to different types of COVID-19 (mis)information affect misinformation beliefs, perceived credibility of the message and intention-to-share it on WhatsApp. Through two mixed-design online experiments in the UK and Brazil (total N = 1454) we first randomly exposed adult WhatsApp users to full misinformation, partial misinformation, or full truth about the therapeutic powers of garlic to cure COVID-19. We then exposed all participants to corrective information from the World Health Organisation debunking this claim. We found stronger misinformation beliefs among younger adults (18–54) in both the UK and Brazil and possible backfire effects of corrective information among older adults (55+) in the UK. Corrective information from the WHO was effective in enhancing perceived credibility and intention-to-share of accurate information across all groups in both countries. Our findings call for evidence-based infodemic interventions by health agencies, with greater engagement of younger adults in pandemic misinformation management efforts.

我们研究了年龄和暴露于不同类型COVID-19（mis）信息的方式如何影响错误信息观念，消息的可信度以及在WhatsApp上分享消息的意图。通过在英国和巴西进行的两次混合设计在线实验（总N = 1454），我们首先将成人WhatsApp用户随机暴露于有关大蒜治疗COVID-19的治疗能力的全部错误信息，部分错误信息或全部事实。然后，我们向所有参与者暴露了来自世界卫生组织的纠正信息，揭穿了这一说法。我们发现在英国和巴西的年轻人中（18-54岁）的错误信息信念更强，在英国的成年人（55岁以上）中，纠正信息可能产生适得其反的效果。来自世界卫生组织的纠正信息有效地提高了两国在所有群体中的可信度和分享准确信息的意愿。我们的发现要求卫生机构进行基于证据的信息流行病干预，并让年轻人更多地参与大流行性错误信息管理工作。