The rate of cases per 100,000 of the population is now at 41.8 compared to just 14.0 the week before.
Health chiefs are now urging the people of Sunderland to continue to follow basic guidance around hands, face, space and fresh air.
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Anyone planning to meet up with family and friends this weekend is urged to do so outside where possible as Covid is less likely to spread.
Gerry Taylor, the City Council's Executive Director of Public Health and Integrated Commissioning for Sunderland, said: "This week we have seen Covid infections rise rapidly with our case numbers almost doubling in a week.
"It’s a stark reminder that Covid is very much still with us so I want to remind everyone, even those of us who have been vaccinated, of the steps we all need to take to stop the virus spreading further.
"Remember hands, face space and fresh air. These basic actions are still really important so please keep washing your hands, wear a face covering when required and keep your distance from others.
"Meet outdoors if you can. It’s the safest way to see others so if you’re meeting friends or family this weekend, I’d encourage you to take advantage of the glorious weather and stay outside. If you are inside, please stick to the rule of six or two households and let the fresh air in by opening a window or door.
"Get both doses of the vaccine when it’s your turn. It really is our best line of defence against Covid so I would urge anyone who is eligible to get their vaccine and get both doses for the most protection.
"If you’re unsure and have questions, it’s really important you get your answers from a reliable source so speak to your GP or a healthcare professional. And it’s never too late, so if you’ve been offered the vaccine but you haven’t had it yet – don’t delay and make your appointment today.
Gerry also stressed the importance of testing and self isolating if you or someone in your household has symptoms however mild they appear.
She said: "Get tested and stay at home if you need to. If you have any symptoms of Covid, even if they are very mild or if you have a positive result from a home test, you must stay home along with everyone you live with and get a PCR test.
"I know staying at home isn’t easy for everyone and we’ve got information on our website about the support which is available should you need it. We’ve also added some tips to help you prepare in advance so you’ll be ready in case you need to stay at home.
"So whether your plans for this weekend involve seeing friends and family, watching the Euros or a spot of shopping, please do so safely and help us keep Covid under control."