Apple's Chief Operating Officer Jeff Williams unveils Apple Watch Series 6 during a special event at the company's headquarters of Apple Park in Cupertino, California, on Tuesday. Reuters

Apple Inc on Tuesday introduced a new Apple Watch Series 6 that monitors blood oxygen for $399 and a lower-cost Apple Watch SE for $279, kicking off a product lineup for a holiday shopping season that will be unlike any other due to COVID-19.

Apple said both new watches can be pre-ordered starting Tuesday and will be available on Friday. Apple also introduced a service called Apple Fitness+ powered by its watches that will deliver virtual workouts.

Apple was expected to update several products including iPads and headphones at an event on Tuesday broadcast from its Cupertino, California, headquarters. Its biggest seller - the iPhone - is expected to be announced next month after executives have said its launch will be delayed by several weeks because of pandemic-related disruptions.

 Jay Blahnik unveils Apple Fitness+ during a special event at the company's headquarters on Tuesday. Reuters

Apple shares have soared this year even as the virus has crippled economies around the world, thanks in large part to booming sales of work-from-home items.

Apple shares were up 2% on Tuesday after climbing more than 50% for the year, well ahead of the 23% gain for the Nasdaq. Even though Apple stock has fallen from a record high earlier this month, it remains near its $2 trillion stock market valuation.

How the new products sell during the holiday shopping season in many markets will largely define how well Apple performs for its entire fiscal year, which started this month.

Apple said the Series 6 watch's new ability to monitor blood oxygen using infrared light should be used for fitness and wellness purposes. Doctors in India and other countries have used pulse oximeters to remotely check on COVID-19 patients and ensure their oxygen saturation level does not fall too low.

Ted Merendino unveils the eighth-generation iPad during a special event at the company's headquarters on Tuesday. Reuters

A level between 95% and 97% is considered normal by the American Lung Association. Patients below 95% should call their doctor and those under 90% should go to the emergency room, health experts advise.

Low oxygen levels are usually not the sole indicator of having COVID-19, the association said.

The previous version of the Apple Watch can already take measurements similar to electrocardiogram.

Apple's Heart Study found that the watch could accurately detect atrial fibrillation, the most common type of irregular heartbeat, according to a study that explored the role of wearable devices in identifying potential heart problems. Atrial fibrillation increases the risk of stroke more than fivefold, according to the American Heart Association.

Reuters