Actress Jennifer Garner made sure to celebrate her assistant Maureen Grosser's birthday by planning a sweet drive-by outside her California home, despite normal life being paralysed by the COVID-19 pandemic.

Maureen is currently isolating with Jennifer and her kids as Los Angeles remains on lockdown amid the coronavirus pandemic, but the actress was sure not to let the global health crisis halt the day's celebrations, reports aceshowbiz.com.

Garner had around 15 cars full of people drive by the house and sing "Happy Birthday to You" to Grosser, all from a safe distance.

She also shared a message in honour of her pal on Instagram, writing: "On my good days, people ask if we're sisters, but more often than I care to admit—the assumption is mother/daughter. We aren't actually related --but I'll claim her."

"For seven years, Maureen Grosser has planned my life, been my constant travel buddy (Mo wouldn't miss a Save the Children site visit for anything), helped me look organised, and competent at things like SignupGenius, and, most of all, this very platform. People ask what social media company I use -- well, I sit in the excellent company of @mogrosser, noodling on ideas, and edits, and captions, playing to our morphed-into-one funny bone.

"Mo isn't one to want attention, but she's in lockup with me at my crazy house and it's her birthday. Plus it's time I post something without her approval, for crying out loud. Happy birthday, Mosie, we are lucky to have you here with us, today and always.