To the Editor — The world is waiting for a vaccine against SARS-CoV-2. In anticipation of successful trial results, preparations are being made for an unprecedented effort to achieve universal coverage and protection. But the interim measures to mitigate COVID-19 have brought their own severe and negative aftershocks. Global lockdowns and closures of schools and protective services have shone light on the vulnerability of children. Challenges of parenting under the strain of the epidemic are near-universal, and most harsh parenting is not malicious, but triggered by stress, poverty and mental health distress. In the extreme, the situation of fragile families affected by violence and neglect has worsened1, abusers have had increased impunity and victims have been cut off from supportive teachers, social workers and friends. The looming economic fallout and uncertainty is adding yet more pressure onto such family settings, with lifetime and intergenerational consequences for the children affected. But there is a cost-effective and scalable response.

From infancy, children experience the absence of protective and nurturing primary caregivers as a serious threat. Neglect or violence chronically activates the stress response system. This toxic stress fundamentally alters neuroendocrine, neurotransmitter systems and pro-inflammatory cytokines, with lasting negative consequences on emotional, intellectual and physical development2. Research from the US Centers for Disease Control and Prevention (CDC), WHO and others has shown strong correlations between these adverse childhood experiences and increased lifetime rates of depression, suicide, alcohol and drug use, obesity, HIV infection, chronic obstructive pulmonary disease and heart disease3. Before COVID-19, systematic reviews identified that a billion children a year were already victims of violence4, costing 2–5% of global GDP5. The role of child protection social workers is essential, but by the time they are involved, violence has already taken place: this is primarily response rather than prevention.

What we need is a ‘vaccine’ against neglect and abuse in the lives of children. And recent research shows that a cost-effective preventative service does exist. Just as with a COVID-19 vaccine, this builds on decades of previous research6. Evidence-based parenting programmes support families with the common challenges of raising children while respecting parents’ capacity to solve problems. They also provide effective strategies for improving relationships, reducing conflict, managing family finances and relieving parenting stress7. In the past two years, randomised controlled trials have shown that families accessing parenting programmes have reductions in violence, mental health problems, alcohol use and extreme poverty8,9. There is good evidence of effectiveness across high-, middle- and low-income countries. Although parenting support cannot provide herd immunity against childhood trauma, it is the best option we know for preventing this serious threat to public health. The return on investment for government budgets and societal wellbeing would be substantive.

There has been global agreement on the need for a COVID-19 vaccine to be universally available, not-for-profit and equitably accessible in low- and middle-income countries. These conditions should also apply to a parenting ‘vaccine’. Delivery cost in countries that have scaled up non-commercial parenting programmes nationally, such as the Philippines and South Africa, is around $18 per family—similar to the cost of a standard flu vaccine. New initiatives have shown the capacity to provide evidence-based parenting support through remote delivery, reaching 57 million families across 180 countries within the first 12 weeks of COVID-19 lockdowns10.

The world needs a universal, public health approach, both to prevent COVID-19 and to break the intergenerational transmission of toxic stress that the pandemic has exposed.