Supermarket workers should be trained to identify and help domestic abuse victims during the pandemic through a code word system, MPs have been told.
Dame Vera Baird, Victims Commissioner for England and Wales, said a scheme based on the Ask for Angela campaign to combat sexual violence was badly needed to help people during the lockdown.
Going shopping was one of few "channels of escape" for victims, she said.
Calls to domestic abuse help lines have increased in the past three weeks.
The government has set aside an extra £2m to support domestic abuse services while the Home Office has launched an initiative called 'You Are Not Alone' to help those experiencing domestic abuse.
Speaking at the government's daily coronavirus briefing, Health Secretary Matt Hancock said those at risk would get the "right support", adding "there are so many costs to this awful epidemic and this is sadly one of them".
Earlier, Dame Vera told MPs on the Home Affairs Committee that the pandemic posed a unique challenge in terms of identifying and protecting vulnerable women and men.
She said there was evidence of a marked increase in killings of women by men, including by current or previous partners, since strict restrictions on people's movements were imposed on 23 March.
She said there had been, on average, five such deaths a week since then, much higher than the average of two a week over the equivalent period in previous years.
She said the figures - which were based on research by the Counting Dead Women project - showed the "scale of the crisis".
The police have said they have not, as yet, seen a spike in domestic violence crimes since the virus struck, while overall crime reported to police in England and Wales has dropped by around 20% in recent weeks.
Charities believe that perpetrators will use the lockdown to further isolate their victims and stop them getting help.
But Dame Vera said supermarkets and pharmacies could be asked to play a role in helping those "locked" in their homes and only making occasional forays.
"You may be a very controlled person but the likelihood is that you are still being sent out to buy the food," she said.
She said if a victim was able to visit a supermarket she or he could use an agreed code word to discreetly ask for help, enabling a member of staff to alert either the police or a woman's refuge.
A similar system was introduced in bars and other venues in England in 2016, with anyone who feared they were in danger of being a victim of a sexual assault being encouraged to ask for 'Angela' as a sign they needed help.
Dame Vera urged ministers to talk to retailers about such a system, which she said was recently introduced in France.
While many victims would not feel able to speak directly to a stranger, she said checkout staff and other workers would be able to respond quickly if they were prompted with a code word.
"We need to be flexible as people are locked in their homes and this is one channel of escape," she added.
Dame Vera also warned that women's refuges were largely full up and she appealed to ministers to do more to persuade hotel chains and universities to offer accommodation where available.
Also appearing before MPs, the Domestic Abuse Commissioner Nicole Jacobs said domestic violence and Covid-19 were a "deadly combination" and victims should be given more time to report abuse to the police.
Labour's Yvette Cooper, who chairs the committee, said while it supported the government's effort to save lives by restricting movement, she said the reality was that many women were "not safe" in their homes.
Campaigners welcomed last week's promise by government of £750m in emergency financial support for charities but said they were worried about how it would be "fairly" allocated.
Baljit Banga, executive director of Imkaan, said many BAME organisations were not part of the current system of support administered by local authorities or police and crime commissioners.
"If it is mainly through existing frameworks then it will not get to BAME organisations. There are real concerns."
For information and support on domestic abuse, contact:
- Police: 999 press 55 when prompted if you can't speak
- Refuge UK wide 24-hour helpline: 0808 2000 247
- Welsh Women's Aid Live Fear Free 24-hour helpline: 0808 80 10 800
- Scotland National Domestic Abuse and Forced Marriages 24-hour helpline: 0800 027 1234
- Northern Ireland Domestic Abuse 24-hour helpline: 0808 802 1414
Online webchats and text services are also available.