Karen Parker tells you that she needs genetic material from infected water tanks so that she can test them and create an anti-virus to stop the infection. Genetic material, which are similar of golden orbs, can be collected by destroying infected water tanks before they hatch. Use Groundspike to destroy the tanks from a distance a few walkers will try and attack you, not much of a match at this point in the game. A few tanks are surrounded by the soldiers, you can either use stealth consume, kill them all in open combat or through on of the air conditioning units from a close rooftop.
Once the meter is filled, go to the Hive and you will see the military attacking the Hive. You can either battle the military and then collect the genetic material that is expelled from the Hive, or you can just avoid the military and just collect the genetic material before the Hive is destroyed. A military disguise can help a lot if you want to avoid combat with them, mind the Hunters however. If you have a military disguise, you can hijack the tanks firing at the hive and control the damage done by the military to the hive. Collect genetic material until the meter fills up completely.