Yes, bio-plastics are just as suitable for use as cross contamination barriers as petroleum plastics are. Viruses and bacteria are too large to pass through plastics on a molecular level.
What is important to note is that within the category of bio-plastics and petroleum plastics there is a wide variety of different types of plastic. For example PLA (poly-lactic acid) is the most widely used type of plant based bio-plastic on the market, it is compostable and can be produced in many forms including films and hard plastics. It is compostable and made of sustainable materials. PE plastic (polyethylene) is a petroleum based plastic that can also be made into films and hard plastics but is derived from oil and will take hundreds of years to break down. while they are made of different materials they both share similar physical properties that make them excellent barriers. Most importantly these plastics are hydrophilic - meaning they are impervious to liquids. You can wash a PLA bag with soap and water in exactly the same way you'd wash a ziploc bag and its structural integrity will not be compromised. Bio-plastics will only begin to decompose once discarded and exposed to bacteria and other natural elements.